Copyright © 2020 National Fire Protection A5sociation®. All Rights Reserved.

NFPA® 90A

Standard for the

Installation of Air-Conditioning and Ventilating Systems

2021 Edition

This edition of NFPA 90A, Standard for the Installation of Air-Conditioning and Ventilating Systems, wa5 prepared by the Technical Committee on Air Conditioning. It was issued by the Standards Council on June 1 , 2020, with an effective date of June 21, 2020, and supersedes all previous editions.

This edition ofNFPA 90A was approved as an American National Standard on June 21, 2020.

Origin and Development of NFPA 90A

90A-l

This standard dates from 1899, when committee attention was first given to blower and exhaust systems. Prior to 1936, the subject of air-conditioning was covered in NFPA standards on blower systems. In 1937, it was decided to prepare a separate standard on air-conditioning, warm air heating, and ventilating systems. This standa1-d was initially adopted in 1937 with subsequent amendments in 1938, 1939, 1940, 1942, 1950, 1952, 1955, 1956, 1960, 1961, 1963, 1964, 1965, 1968, 1971, 1973, 1976, 1980, 1984, and 1989. The 1993 and 1996 editions were reconfirmations of the 1989 edition. The 1999 edition contained changes that were mainly editorial in nature.

The 2002 edition incorporated format changes to com ply with the Manual of Style for NFPA Technical Committee Documents and new provisions for the removal of accessible abandoned materials in concealed spaces and plenums.

The only changes to the 2006 edition were to update "flame spread rating" to "flame spread index."

The major change in the 2009 edition was to replace the references to NFPA 255 with ANSI/UL 723 and ASTM E84, because NFPA 255 was withdrawn. All three test standards were quite similar.

The changes in the 2012 edition were edition updates of the referenced standards.

For the 2015 edition, the changes were primarily editorial alterations, reference updates, and clarifications of existing language. Also, a section and test method for air dispersion systems was added.

For the 2018 edition, the changes were primarily editorial alterations, reference updates, clarifications of existing language, and corrections for changes of terminology. Also, an option for testing flame spread of plastic pipe for use in plenums was added.

For the 2021 edition, the changes were primarily editorial alterations, reference updates, and updates to existing language. In the referenced publications, all UL publications have been updated to remove the term ANSI for clarification.

NFPA and National Fire Protection Association are registered trademarks of the National Fire Protection Association, Quincy, Massachusett.s 02169.

90A-2 INSTALLATION OF AIR-CONDITIONING AND VENTlLATING SYSTEMS

Technical Committee on Air Conditioning

Ralph D. Gerdes, Chair Ralph Gerdes Consulcants, LLC, IN [SE]

Kevin Carr, Administrative Secretary National Fire Protection Association, MA

Joseph F. Andre, Steel Tube Institme, WA [M] Rep. Steel Tube Institute of North America

Rendell K. Bourg, National Fire Protection Company Inc., HI [M] Rep. Automatic Fire Alarm Association, Inc.

Alberto Cusimano, Dupont International SA, Switzerland [U]

Dennis Dawe, CBRE, IN [U]

Michael Earl Dillon, Dillon Consulting Engineers, l nc., CA [SE]

James T. Dollard,Jr., IBEW Local Union 98, PA [L) Rep. International Brotherhood of Electrical Workers

Jonathan Flannery, AHA - ASHE, AR [ U]

John C. Harrington, FM Global, MA (I]

Jonathan Hartsell, Rodgers, NC [IM]

Marcelo M. Hirschler, GBH International, CA [M] Rep. North American Flame Retardant Alliance/Plenum Cable

Assn.

Eli P. Howard, III, Sheet Metal & Air Conditioning Contractors Natl. Assn., VA [IM]

Anthony Hurst, Mason & Hanger, KY [SE)

Kevin D. Kalakay, State of Michigan, tvU [E)

Ralph A Koerber, ATCO Rubber Products, Inc., TX [M] Rep. Air Diffusion Council

William E. Koffel, Koffel Associates, Inc., MD [M) Rep. Plastics Industry Association (Plastics)

Ajay V. Prasad, JENSEN HUGHES, MD [SE] Rep.JENSEN HUGHES

Michael Schmeida, Gypsum Association, OH [M]

Dwayne E. Sloan, UL LLC, NC [RT)

George A. Straniero, AFC Cable Systems, Inc., NJ [Ml Rep. National Electrical Manufacturers A5sociation

John M. Wright, SMART 20, IN [L]

Alternates

Jay Burris, Wheatland Tube (Div. ofZekelman Industries), OH [M] (AIL to Joseph F. Andre)

Charles C. Cottrell, North American Insulation Manufacturers Assn., VA [M]

(Voting AIL) Timothy Earl, GBH International, MI [M]

(AIL to Marcelo M. Hirschler)

David L. Hall, Apollo America Inc., Ml [Ml (AIL to Rendell K. Bourg)

Amando Lyndyll Hisole, ccrd parmers, TX [SE] (Voting AIL)

Kevin Carr, NFPA Staff Liaison

Michael Lloyd, Honeywell International, Inc., IL [M] (AIL Lo George A. Straniero)

Harold C. Ohde, IBEW 134/ElectricalJointApprenticeship Training & Trust, IL [L]

(AIL to James T. Dollard, Jr.)

Mark Terzigni, Sheet Metal & Air Conditioning Conu·actors Natl. Assn., VA [IM]

(AIL to Eli P. Howard, lll)

William A. Webb, WEBB FLRE Protection Consulting, LLC, FL [IM] (Voting Alt.)

This lirt rt"jJresents the nwmbership at the time the Committe,e was balloted on the.final text of this edition. Since that time, changes in the nwmbershifJ may have ocettrred. A key to cklssifications is found at the back of lhe doettment.

2021 Edition

NOTE: Membership on a committee shall not in and of itself constitme an endorsement of tl1e Association or any document developed by the committee on which the member serves.

Committee Scope: This Committee shall have primary responsibility for document5 on tl1e construction, installation, operation, and maintenance of systems for air conditioning, warm air heating, and ventilating including filters, ducts, and related equipment to protect life and property from fire, smoke, and gases resulting from fire or from conditions having manifestations similar to fire.

CONTENTS

Chapter I Administration .......................................... .

I.I Scope . .................................................................. .

1.2 Purpose . .............................................................. .

1.3 Application . ......................................................... .

1.4 Retroactivity . ........................................................ .

1.5 Equivalency . ........................................................ .

Chapter 2 Referenced Publications ........................... . 2.1 General. ............................................................... .

2.2 NFPA Publications . ............................................. .

2.3 Other Publications . ............................................ .

2.4 References for Extracts in Mandatory Sections.

Chapter 3 Definitions .................................................. .

3.1 General . . .............................................................. .

3.2 NFPA Official Definitions . ................................. .

3.3 General Definitions . ........................................... .

Chapter 4 HVAC Systems ............................................ .

4.1 General Requirements for Equipment. ............ .

4.2 System Components . .......................................... .

4.3 Air Disu-ibution . .................................................. .

90A-4 90A-4 90A-4 90A-4 90A-4 90A-4

90A-4 90A-4 90A-4 90A-5 90A-5

90A-6 90A-6 90A-6 90A-6

90A-7 90A-7 90A-7 90A-8

4.4 Materials. ... ..... ..... .......... ..... ..... ..... ..... ..... ..... ..... .... 90A-1 4

Chapter 5 Integration of a Ventilation and Air-Conditioning System(s) with Building Construction................................................ 90A-15

5.1 Ai1�Handling Equipment Rooms. ....................... 90A-1 5

Contents

5.2 Building Construction . ....................................... .

5.3 Peneu-ations - Protection of Openings . .......... .

5.4 Fire Dampers, Smoke Dampers, and Ceiling Dampers . ............................................................. .

Chapter 6 Controls ...................................................... .

6.1 Wiring . ................................................................. .

6.2 Manual Control. ................................................. .

6.3 Smoke Dampers . ................................................. .

6.4 Smoke Detection for Automatic Control. ......... .

Chapter 7 Acceptance Testing .................................... .

7.1 General. ............................................................... .

7.2 Fire Dampers, Smoke Dampers, and Ceiling Dampers . .. ........................................................... .

7.3 Controls and Operating Systems . ...................... .

Annex A Explanatory Material ................................. .

Annex B Maintenance ............................................... .

Annex C htformational References ......................... .

htdex

90A-3

90A-15 90A-15

90A-16

90A-17 90A-17 90A-17 90A-17 90A-17

90A-18 90A-18

90A-18 90A-18

90A-18

90A-22

90A-23

90A-25

2021 Edition

90A4 INSTALLATION OF AIR-CONDITIONING AND VENTlLATING SYSTEMS

NFPA90A

Standard for the

Installation of Air-Conditioning and Ventilating

Systems

2021 Edition

IMPORTANT NOTE: This NFPA document is made ava.ilable for use subject to important rwtices and legal disclaimers. These rwtices and disclaimers appear in all publications containing this document and may be found under the heading "Important Notices and Disclaimers Concerning NFPA Standards. " They can also be viewed at www.njpa.org! disclaimers or obtained on request from NFPA.

UPDATES, ALERTS, AND FUTURE EDITIONS: New editions of NFPA codes, standards, recommended practices, and guides (i.e., NFPA Standards) are released on scheduled revision cycles. This editian may be superseded by a later one, or it may be amended outside of its scheduled revision cycle through the issuance of Tenta­tive Interim Amendments (TIAs). An official NFPA Standard at any point in time consists of the current edition of the document, together with all TIAs and Errata in effect. To veriJY that this document is the current edition or to determine if it has been amended by TIAs or Errata, please consult the National Fire Codes® Subscription Service or the "List of NFPA Codes & Standards" at wwm nfpa.org/ docinfo. In addition to TIAs and Errata, the document information pages also include the option to sign up for alerts for individual documents and to be involved in the development of the next edition.

NOTICE: An asterisk (*) following the number or letter designating a paragraph indicates that explanatory material on the paragraph can be found in Annex A.

A reference in brackets [ l following a section or paragraph indicates material that has been exu-acted from another NFPA document. Exu·acted text may be edited for consistency and style and may include the 1·evision of internal paragraph refer­ences and other references as appropriate. Requests for inter­pretations or revisions of exu·acted text shall be sent to the technical committee responsible for the source document.

Information on referenced and exu·acted publications can be found in Chapter 2 and Annex C.

Chapter 1 Administration

1.1 * Scope. This standard shall cover construction, installa­tion, operation, and maintenance of systems for air condition­ing and ventilating, including filters, ducts, and related equipment, to protect life and property from fire, smoke, and gases resulting from fire or from conditions having manifesta­tions similar to fire.

1.2 Purpose. This standard shall prescribe minimum require­ments for safety to life and property from fire. These require­ments shall be intended to accomplish the following:

( 1) Restrict the spread of smoke through air duct systems within a building or into a building from the outside

(2) Resu·ict the sp1·ead of fire through air duct systems from the area of fire origin, whether located within the build­ing or outside

(3) Maintain the fit-e-resistive integ1·ity of building compo­nents and elements such as floors, partitions, roofs, walls, and floor- or roof-ceiling assemblies affected by the installation of air duct systems

2021 Edition

(4) Minimize the ignition sources and combustibility of the elements of the air duct systems

(5) Permit the air duct systems in a building to be used for the additional purpose of emergency smoke conu·ol

1.3 Application. This standard shall apply to all systems fo1· the movement of environmental air in structures that serve the following:

( l )* Spaces over 708 m3 (25,000 ft3) in volume (2)* Buildings of Types III, IV, and V construction over three

sto1·ies in height, regardless of volume (3)* Buildings and spaces not covered by other applicable

NFPA standards (4)* Occupants or processes not covered by other applicable

NFPA standards

1.4 Retroactivity. The provisions of this standard shall not be intended to be applied reu·oactively. Where a system is being altered, extended, or renovated, the requirements of this stand­ard shall apply only to the work being undertaken.

1.5 Equivalency. Nothing in this standard shall be intended to prevent the use of new methods or devices, provided that suffi­cient technical data are submitted to the authority havingjuris­diction to demonstrate that the p1·oposed method or device is equivalent in quality, sn-ength, durability, and safety to that prescribed by this standard.

Chapter 2 Referenced Publications

2.1 General. The documents or portions thereof listed in this chapter are referenced within this standard and shall be considered part of the require men ts of this document.

2.2 NFPA Publications. National Fire Protection Association, 1 Batte1ymarch Park, Quincy, MA 02169-747 1 .

NFPA 30, Flammabl,e and Combustible Liquids Code, 2021 edition.

NFPA 3 1 , Standard for the Installation of Oil-Burning Equipment, 2020 edition.

NFPA 54, NationalFWJl Gas Code, 2021 edition. NFPA 7o®, National fiectrical Code®, 2020 edition. NFPA 72®, National Fire Alarm and S ignaling Code®, 2019

edition. NFPA 75, Standard for the Fire Protection of Information Technol­

ogy Equipment, 2020 edition. NFPA 80, Standard for Fire Doors and Other 0/Jening Protectives,

2019 edition. NFPA 101®, Life Safety Code®, 2021 edition. NFPA 105, Standard for Smoke Door Assemblies and Other Open­

ing Protectives, 2019 edition. NFPA 259, Standard Test Method for Potential Heat of Building

Mater ials, 2018 edition. NFPA 262, Standard Method of Test for Flame Travel and Smoke of

Win1s and Cables for Use in Air-Handling Spaces, 2019 edition. NFPA 275, Standard Method of Fire Tests for the Evaluation of

Thermal Barriers, 2017 edition. NFPA 286, Standard MethocL� of Fzre Tests for Evaluating Contri­

bution of Wall and Ceiling Interior Finish to Room Fire Growth, 2019 edition.

NFPA 5000®, Building Construction and Safety Code®, 2021 edition.

REFERENCED PUBLICATIONS 90A-5

2.3 Other Publications.

2.3.l ASHRAE Publications. ASHRAE, 1791 Tullie Circle, NE, Atlanta, GA 30329-2305.

ASHRAE 1 5 (packaged with ASHRAE 34), Safety Standard for Refrigeration Systems and Designation and Classification of Refriger­ants (ANSI Approved), 2019.

ASH RAE Handbook - HVAC Systems and E,quipment, 2016.

2.3.2 ASTM Publications. ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959.

ASTM C4 l l , Standard Test Method for Hot-Surface Pe1formance of High-Temperature T hermal Insulation, 2019.

ASTM D93, Standard Test Methods for Flash Point fry Pensk)i­Martens Closed Cup Tester, 2018.

ASTM E84, Standard Test Method for Su1face Burning Character­istics of Building Materials, 2019b.

ASTM E 1 19, Standard Test Methods for Fire Tests of Building Construction and Materials, 20 l 8c e 1 .

ASTM E 136, Standard Jest Method for Assessing Comlntstibility of Materials U5ing a Vertical Tube Furnace at 750°C, 2019.

ASTM £2231, Standard Practice Jm· Specimen Preparation and Mmmting of Pipe and Duct Insulation Materials to Assess Surface Burning Characteiistics, 2018.

ASTM £2652, Standard Jest Method for Assessing Combustibility of Materials Using a Tube Furnace with a Cone-Shaped Aiiflow Stabil­izer, at 750°C, 2018.

ASTM £2965, Standard Jest Method fm· Determination of Low Levels of Heat Re/,ease Rate fm· Materials and ProducL5 Using an O:rygen Consumption Calorimeter, 2017.

2.3.3 GA Publications. Gypsum Association, 6525 Belcrest Road, Suite 480, Hyattsville, MD 20782.

GA-600, Fire Resistance and Sound Control De.5ign Manual, 2018.

2.3.4 NAIMA Publications. North American Insulation Manu­facturers Association, 1 1 Canal Center Plaza, Suite 103, Alexan­dria, VA 22314.

Fibrmis Glass Duct Construction Standards, 5th edition, 2002.

2.3.5 SMACNA Publications. Sheet Metal and Air Condition­ing Contractors' National Association, 4201 Lafayette Center Drive, Chantilly, VA 20151-1219.

ANSI/SMACNA 016, HVAC Air Duct Leakage Jest Manual, 2nd edition, 2012.

Fibrws Glass Duct Construction Standards, 7th edition, 2003.

HVAC Duct Construction Standards - Metal and Rexi,ble, 3rd edition, 2005.

2.3.6 UL Publications. Underwriters Laboratories Inc., 333 Pfingsten Road, Northbrook, IL 60062-2096.

UL 181 , Factory-Made Air Ducts and Air Connectors, 2013, revised 2017.

UL 181A, Closure Systems fm· Use with Rigid Air Ducts, 2013, revised 2017.

UL 181B, Cl.osure Systems for Use with Flexibl.e Air Ducts and Air Connectors, 2013, revised 2017.

UL 263, Fire Jests of Building Construction and Materials, 201 1 , revised 2018.

UL 555, Fire Dampers, 2006, revised 2016.

UL 555C, Ceiling Dampers, 2014, revised 2017.

UL 555S, Smoke Dampers, 2014, revised 2016.

UL 723, Test for Smface Burning Characteristics of Building Mate-1ials, 2018.

UL 867, .Electrostatic Air Cleaners, 201 1 , revised 2018.

UL 900, Air Filtei· Units, 2015.

UL 1598, Luminaires, 2018.

UL 1820, Fire Jest of Pneumatic Tubing for Flame and Smoke Characteristics, 2004, revised 2017.

UL 1887, Fire Jest of Plastic Sprinklei· Pipe for Visible Flame and Smoke Characte1istics, 2004, revised 2017.

UL 1995, Heating and Cooling Equipment, 2015.

UL 2024, Cable Routing Assemblies and Communications Race­ways, 2014, revised 2015.

UL 2043, Fire Jest for Heat and Visibl.e Smoke Release for Discrete Products and Their Accessmies Install.ed in Air-Handling Spaces, 2013.

UL 2518, Air Dispersion Systems, 2016.

UL 2846, Fire Jest of Plastic Water Dist1ibution Plumbing Pipe for Visible Flame and Smoke Charactmistics, 2014, revised 2016.

UL 60335--2-40, Hotl5ehold and Similar Electrical AfrPliances, Part 2-40: Particidar Requirements fm· Electrical Heat Pumps, Ai1� Conditioners and Dehumidifim-s, 201 7.

2.3. 7 Other Publications.

Mmiam-Webster's Collegiate Dictionary, 1 1th edition, Men-iam­Webster, Inc., Springfield, MA, 2003.

2.4 References for Extracts in Mandatory Sections.

NFPA 80, Standard for Fi:re Doors and Other Opening Protectives, 2019 edition.

NFPA 90B, Standard for the Installation of Warm Air Heating and Air-Conditioning Systems, 2021 edition.

NFPA 101®, Life Safety Code®, 2021 edition. NFPA 2 1 1 , Standard for Chimneys, Fireplaces, \.-ents, and Solid

Fuel-Burning Appliances, 2019 edition. NFPA 500o®, Building Construction and Safety Code®, 2021

edition.

2021 Edition

90A-6 INSTALLATION OF AIR-CONDITIONING AND VENTlLATING SYSTEMS

Chapter 3 Definitions

3.1 General. The definitions contained in this chapter shall apply to the terms used in this standard. Where terms are not defined in this chapter or within another chapte1� they shall be defined using their ordinarily accepted meanings within the context in which they are used. Merriam-Webster's Colli!giale Dictiona?)� 1 1 th edition, shall be the source for the ordinarily accepted meaning.

3.2 NFPA Official Definitions.

3.2.l * Approved. Acceptable to the autho1-ity having jurisdic­tion.

3.2.2* Authority Having Jurisdiction (AHJ). An organization, office, or individual responsible fo1- enforcing the requirement5 of a code or standard, or for approving equipment, materials, an installation, or a procedure.

3.2.3* Listed. Equipment, materials, or services included in a list published by an organization that is acceptable to the authority having jurisdiction and concerned with evaluation of products or services, that maintains periodic inspection of production of listed equipment or materials or periodic evalua­tion of services, and whose listing states that either the equip­ment, material, or service meets approp1-iate designated standards or has been tested and found suitable for a specified purpose.

3.2.4 Shall. Indicates a mandatory requirement.

3.2.5 Should. Indicates a recommendation or that which is advised but not required.

3.2.6 Standard. An NFPA Standard, the main text of which contains only mandatOl)' provisions using the word "shall" to indicate requirements and that is in a form generally suitable for mandatory reference by another standard or code or for adoption into law. Nonmandatory provisions are not to be considered a part of the requirements of a standard and shall be located in an appendix, annex, footnote, infonnational note, or other means as permitted in the NFPA Manuals of Style. When used in a generic sense, such as in the phrase "standards development process" or "standards development activities," the term "standards" includes all NFPA Standards, including Codes, Standards, Recommended Practices, and Guides.

3.3 General Definitions.

3.3.1 Accessible. Capable of being removed or exposed with­out damaging the building structure or finish, or not perma­nently closed in by the structure or finish of the building.

3.3.2 Air Cleaner. A device used to reduce or remove airborne solids from heating, ventilating, and air-conditioning systems by electrostatic means.

3.3.3* Air Connector. A conduit for transferring air bet\veen an air duct or plenum and an air terminal unit or an air inlet or air outlet.

3.3.4 Air Distribution System. A continuous passageway for the transmission of air that, in addition to air ducts, can include air connectors, air duct fittings, dampers, plenums, fans, and accessory air-handling equipment but that does not include conditioned spaces.

2021 Edition

3.3.5 Air Duct. A conduit or passageway for conveying air to 01- from heating, cooling, ai1--conditioning, or ventilating equip­ment, but not including the plenum.

3.3.6 Air Duct Covering. A material such as an adhesive, insu­lation, banding, a coating(s), film, or a jacket used to cover the outside surface of an air duct, fan casing, or duct plenum.

3.3. 7 Air Duct Lining. A material such as an adhesive, insula­tion, a coating(s), or film used to line the inside surface of an air duct, fan casing, or duct plenum.

3.3.8 Air Filter. A device used to reduce or remove airborne solids from heating, ventilating, and air-conditioning systems. f90B, 2021 ]

3.3.9* Air Inlet. Any opening through which air is removed from a space and returned to an air distribution system.

3.3.10* Air Outlet. Any opening through which air is deliv­ered to a space from an air distribution system.

3.3.11 Air Terminal Unit. An appliance receiving, condition­ing, and delivering air supplied through an air disu-ibution system.

3.3.12 Air Thansfer Opening. An opening designed to allow tl1e movement of environmental air betvveen t\vo contiguous spaces.

3.3.13 Continued Progressive Combustion. A flame front progressing more than 3.2 m (10.5 ft) beyond the centerline of the burners during a test in accordance with ASTM E84, Stand­ard Test Method for Swf ace Burning Characteristics of Building Mate­rials, or UL 723, Test for Surface Burning Characte·ristics of Building Materials.

3.3.14 Damper.

3.3.14.1* Ceiling Damper. A listed device installed in a ceil­ing membrane of a fire resistance-rated floor-ceiling or roof-ceiling assembly to automatically limit the radiative heat transfer through an air inlet/outlet opening.

3.3.14.2 Combination Fire and Smoke Damper. A device that meets both fire damper and smoke damper requirements.

3.3.14.3* Fire Damper. A device installed in an air distribu­tion system and designed to close automatically upon detec­tion of heat, to interrupt migratOl)' ai1-flow, and to restrict the passage of flame.

3.3.14.4* Smoke Damper. A device within an air-distribution system to control the movement of smoke. r 5000, 2021 l

3.3.15 Environmental Air. Air that is supplied, returned, recir­culated, or exhausted from spaces for the purpose of modifying the existing atmosphere within the building.

3.3.16 Fan. A blower or exhauster assembly comprising blades or runners and housings 01- casings. [211, 2019]

3.3.17* Fire Resistance Rating. The time, in minutes or hours, that materials or assemblies have withstood a fire expo­sure as established in accordance with the test procedures of ASTM E 119, Standard Test Methods for Fire Tests of Building Construction and Materials, or UL 263, Fire Tests of Building Construction and Materials.

HVAC SYSTEMS 90A-7

3.3.18 Fire Wall. A wall separating buildings or subdividing a building to prevent the spread of fire and having a fire resist­ance rating and structural stability.

3.3.19* Flame Spread Index. A comparative measure expressed as a dimensionless number derived from visual meas­urements or the spread of flame versus time in ASTM E84, Standard Test Method for Swface Burning Characteristics of Building Materials, or UL 723, Test for Smface Burning Character istics of Building Material�.

3.3.20 Foam Plastic Insulation. A cellular plastic, used for thermal insulating or acoustical applications, having a density of 20 lb/ft3 (320 kg/m3) or less, containing open or closed cells, and formed by a foaming agent. [5000, 2021]

3.3.21 * Limited-Combustible (Material). See 4.4.2.

3.3.22* Noncombustible Material. See 4.4. l .

3.3.23* Plenum. A compartment or chamber to which one or more air ducts are connected and that forms part of the air distribution system.

3.3.23.1 Air-Handling Unit Room Plenum. An individual room containing an air-handling unit(s) used to gather air from various sources and combine the air within the room before returning it to the air-handling unit.

3.3.23.2 Apparatus Casing Plenum. A sheet metal construc­tion attached directly to a fan enclosure, fan coil unit, air­handling unit, or furnace bonnet for the purpose of connecting distribution ducts.

3.3.23.3 Ceiling Cavity Plenum. The space between the top of the finished ceiling and the underside of the floor above or the roof and used to supply air to the occupied area or to return air to or exhaust ai1· from the occupied area.

3.3.23.4 Raised Fl.oar Plenum. The space between the top of the finished floor and the underside of a raised floor and used to supply air to the occupied area or to return air to or exhaust air from the occupied area.

3.3.24 Smoke. The airborne solid and liquid paniculates and gases evolved when a material undergoes pyrolysis or combus­tion, together with the quantity of air that is entrained or other­wise mixed into the mass.

3.3.25* Smoke Barrier. A continuous membrane, or a membrane with discontinuities created by protected openings, whe1·e such membrane is designed and constructed to restrict the movement of smoke. [5000, 202 1 ]

3.3.26 Smoke Control. A system that utilizes fans to produce pressure diffe1·ences so as to manage smoke movement.

3.3.27* Smoke Detector. A device that senses visible or invisi­ble particles of combustion.

3.3.28* Smoke Developed Index. A comparative measure expressed as a dimensionless number, derived from measure­ments of smoke obstruction versus time in ASTM E84 Standard Test Method for Su1face Burning Characteristics of Building Materials, or UL 723, Test for Surface Burning Characteristics of Building Mate­rials.

Chapter 4 HVAC Systems

4.1 General Requirements for Equipment.

4.1.1 Access. Equipment shall be arranged to afford access for inspection, maintenance, and repair.

4.1.2 Equipment shall be selected and installed based on its application with respect to the manufacturer's installation instructions and listing, as applicable.

4.1.3 Protection.

4.1.3.1 Equipment shall be guarded for personnel protection.

4.1.3.2 Equipment shall be guarded against the intake of foreign matter into the system.

4.1.4 Electrical wiring and equipment shall be installed in accordance with NFPA 70.

4.1.5 Air-handling equipment rooms shall meet the require­ments of Section 5.1 .

4.2 S�tem Components.

4.2.l Outside Air Intakes.

4.2.1.1 Outside air intakes shall be protected by screens of corrosion-resistant material not large1· than 12.7 mm (0.5 in.) mesh.

4.2.1.2* Outside air intakes shall be located so as to minimize the inu·oduction of fit·e or smoke into the building.

4.2.1.2.1 Outside air intakes shall be equipped with an approved fire and/or smoke damper where not located to meet the requfrements of 4.2.1.2. (See Section 6.3 for smoke damper operation to restrict the intake of smoke.)

4.2.2 Air Cleaners and Air Filters.

4.2.2.l Electrostatic air cleaners shall be listed in accordance with UL 867, El.ectrostatic Air Cleaners.

4.2.2.1.1 Electrostatic air cleaners shall be installed in conformance with the conditions of the manufacturer's listing.

4.2.2.2* Air filters shall comply with UL 900, Air Filter Units.

4.2.2.3 Liquid adhesive coatings used on air filters shall have a minimum flash point of 163°C (325°F) as determined by ASTM 093, Standard Test Methods for Flash Point by Pensky-Martens Closed Cup Tester.

4.2.2.4 V1lhere air filters are flushed with liquid adhesives, the system shall be arranged so that the air cleaner cannot be flushed while the fan is in operation.

4.2.2.5 Combustible adhesive coatings shall be stored in accordance with NFPA 30.

4.2.3 Fans.

4.2.3.l Installation.

4.2.3.1.1 Fans shall be installed in accordance with the appli­cable NFPA standards and d1e manufacturer's instructions.

4.2.3.1.2 Fans shall be approved for the specific installation.

4.2.3.2 Access. Fans shall be located, arranged, and installed to afford access for inspection and maintenance.

2021 Edition

90A-8 INSTALLATION OF AIR-CONDITIONING AND VENTlLATING SYSTEMS

4.2.3.3 Exposed Inlets. Exposed fan inlets shall be protected with metal screens to pi-event the entry of paper, trash, and foreign materials.

4.2.4 Air-Cooling and Heating Equipment.

4.2.4.1 Installation.

4.2.4.1.1 Heating and cooling equipment shall be installed in accordance with the applicable NFPA standards and the manu­facturer's instructions.

4.2.4.1.2 The equipment shall be approved for the specific installation. (See 4.3.3.1.)

4.2.4.2 Materials. Materials used in the manufacturing of fan coil units, self-contained air-conditioning Llllit5, furnaces, heat pumps, humidifiers, and all similar equipment shall meet the requirements of 4.3.3.1 and 4.3.3.2 unless otherwise specified in 4.2.4.2.1 or 4.2.4.2.2.

4.2.4.2.1 The requirements of 4.3.3.1 and 4.3.3.2 shall not apply to equipment tested and listed in accordance with UL 1995, Heating and Cooling Equipment, or UL 60335-2-40, Household and Similar E'lectrical Appliances, Part 2-40: Particular Requirements for Electrical Heat Pumps, Air-Conditioners and Dehu­midifiers.

4.2.4.2.2 Unlisted solar energy air distribution system compo­nents shall be accompanied by supportive information demon­strating that the components have flame spread and smoke developed indexes that are not in excess of those of the air duct system permitted by this standard.

4.2.4.3 Mechanical Cooling.

4.2.4.3.1 Mechanical refrigeration used with air duct systems shall be installed in acco1-dance with recognized safety prncti­ces.

4.2.4.3.2 Installations conforming to ASHRAE 15 (packaged with ASHRAE 34), Safety Standard for Refr igeration Systems and Designation and Classification of Refrigerants, shall be considered to be in compliance with the requirement in 4.2.4.3. 1 .

4.2.4.4 Furnaces.

4.2.4.4.1 Oil-burning heating furnaces combined with cooling unit5 in the same air duct system shall be installed in accord­ance with NFPA 31.

4.2.4.4.2 Gas-burning heating furnaces combined with cooling unit5 in the same air duct system shall be installed in accord­ance with NFPA 54.

4.2.4.5 Duct Heaters.

4.2.4.5.1 ·where electrical resistance or fuel-burning heaters are installed in air ducts, the air duct coverings and their instal­lation shall comply with the provisions of 4.3.5.3.

4.2.4.5.2 The installation of elecu-ical duct heaters shall comply with the provisions of Part VI, "Duct Heaters," of Article 424 of NFPA 70.

4.2.4.6 Evaporative Coolers. Combustible evaporation media shall not be used unless they meet the requirements of 4.2.2.2.

4.2.4.7 Heat Recovery Equipment. Equipment not covered by othe1- provisions of this standard and used fo1- heat transfer or air movement shall be constructed so that all material in the air path meets the requirements of Section 4.2.

2021 Edition

4.3* Air Distribution.

4.3.1 Air Ducts.

4.3.1.1 Air ducts shall be constructed of iron, steel, aluminum, copper, concrete, masonry, or clay tile, except as otherwise permitted in 4.3.1.2 or 4.3.1.3.

4.3.1.2 Class 0 or Class 1 rigid or flexible air duct5 tested in accordance with UL 181, Factmy-Made Air Ducts and Air Connec­tors, and installed in conformance with the conditions oflisting shall be permitted to be used for ducts where air temperature in the ducts does not exceed 121 °C (250°F) or where used as vertical ducts setving not more than two adjacent stories in height.

4.3.1.3 Gypsum Board Air Ducts.

4.3.1.3.1 Gypsum board having a flame spread index not exceeding 25 without evidence of continued progressive combustion and a smoke developed index not exceeding 50 when tested in accordance with ASTM E84, Standard Test Method for Smjace Burning Characteristics of Building Materials, or UL 723, Test for Surface Burning Characteristics of Building Materi­als, shall be permitted to be used for negative pressure exhaust and return ducts where the temperature of the conveyed air does not exceed 52°C ( 125°F) in normal service.

4.3.1.3.2 The air temperature limits of 4.3.1.3.1 shall not apply where gypsum board material i.s used for emergency smoke exhaust air ducts.

4.3.1.4 All ai1· duct materials shall be suitable for continuous exposure to the temperature and humidity conditions of the environmental air in the air duct.

4.3.1.5 The materials, thickness, construction, and installation of ducts shall provide structural strength and durability.

4.3.1.5.1 Air ducts shall be considered to be in compliance with 4.3.1.5 where constructed and installed in accordance with the ASHRAE Handbook - HVAC Systems and Equipment and with one of the following as applicable:

( 1 ) NAIMA Fi.brous Glass Duct Construction Standards (2) SMACNA Fibrous Glass Duct Construction Standards (3) SMACNA HVAC Duct Construction Standards - Metal and

flexible (4) ANSI/SMACNA 016, HVACAi:rDuct Leakage Test Manual

4.3.1.6 Whe1-e no standard exists for the construction of air ducts, the ducts shall be constructed to withstand both the maximum positive and the maximum negative pressures of the system at fan shutoff.

4.3.1.7 A duct enclosure used for the multiple distribution or gathering of ducts or connectors shall be consU"UCted of mate­rials and methods specified in 4.3.1.

4.3.1.7.1 Electrical wires and cables and optical fiber cables within a duct enclosure shall comply with 4.3.4.

4.3.1.8 Air Dispersion Systems. Air dispersion systems shall meet the following criteria:

( 1 ) They shall only be installed in enti1-ely exposed locations. (2) They shall always operate under positive pressure. (3) They shall not penetrate fire resistance-rated construc­

tion. ( 4) They shall not pass through fire resistance-rated

consu-uction.

HVAC SYSTEMS 90A-9

(5) They shall be listed and labeled in accordance with UL 2518, Air Dispersion S)•stems.

4.3.2 Air Connectors.

4.3.2.1 Air connectors shall be permitted to be used as limited-use, flexible air ducts that shall not be required to con.form to the provisions for air ducts where they meet the requirements of4.3.2. l . l through 4.3.2.1.7.

4.3.2.1.1 Air co1mectors shall conform to the requirements for Class 0 or Class 1 air connectors when tested in accordance with UL 181, FactoJ)•-Made Air Ducts and Air Connectors.

4.3.2.1.2 Class 0 or Class 1 air connectors shall not be used for ducts containing air at temperatures in excess of 121°C (250°F).

4.3.2.1.3 Air connector runs shall not exceed 4.27 m ( 1 4 ft) in length.

4.3.2.1.4 Air connectors shall not pass through any wall, parti­tion, or enclosw·e of a vertical shaft that is required to have a fire resistance rating of 1 hour or more.

4.3.2.1.5 Air connectors shall not pass through floors.

4.3.2.1.6 An air connector shall not be intermpted by a short collar or any other fitting on one side and then connected to another air connector on the other side where penetrating a floor or a wall, partition, or enclosure of a vertical shaft that is required to have a fire-resistance rating of 1 hour.

4.3.2.1.7 Multiple air connector runs shall not be spliced together to exceed the length limitation in 4.3.2.1.3.

4.3.2.2 Vibration isolation connectors in duct systems shall be made of materials having a maximum flame spread index of 25 and a maximum smoke developed index of 50.

4.3.2.3 Wiring shall not be installed in air connectors.

4.3.3 Supplementary Materials for Air Distribution Systems.

4.3.3.1 * Pipe and duct insulation and coverings, duct linings, vapor retarder facings, adhesives, fasteners, tapes, and supple­mentary materials added to air ducts, plenums, panels, and duct silencers used in duct systems, unless otherwise provided for in 4.3.3. 1 . 1 or 4.3.3.1.2, shall have, in the form in which they are used, a maximum flame spread index of 25 without evidence of continued progressive combustion and a maximum smoke developed index of 50 when tested in accordance with ASTM E84, Standard Test Method fm· Sinface Burning Characteris­tics of Building Materials, or with UL 723, Test for Swface Burning Characteristics of Bu ilding Materials. Pipe and duct insulation and coverings, duct linings and their adhesives, and tapes shall use the specimen preparation and mounting procedures of ASTM E223 l , Standard Practice for Specimen Preparation and Mounting of Pipe and Duct Insulation Materials to Assess Swface Burning Charac­teristics.

4.3.3.1.1 The flame spread index and smoke developed index requirement5 of 4.3.3.1 shall not apply to air duct weatherproof coverings where d1ey are located entirely out5ide a building, do not penetrate a wall or roof, and do not create an exposure hazard.

4.3.3.1.2 Smoke detectors required by 6.4.4 shall not be required to meet flame spread index or smoke developed index requirements.

4.3.3.2 Closure systems for use with rigid and flexible air ducts tested in accmdance with UL 181, Factmy-Made Air Ducts and Air Connectors, shall have been tested, listed, and used in accord­ance with the conditions of their listings, in accordance with one of the following:

(1) UL 181 A, Closure Systems for Use with Rigid Air Ducts (2) UL 181B, Closure Systems for Use with Flexible Air Ducts and

Air Connectors

4.3.3.3 Coverings and linings for air duct5, pipes, plenums, and panels, including all pipe and duct insulation materials, shall not flame, glow, smolder, or smoke when tested in accord­ance wi th ASTM C41 l , Standard Te.st Method for Hot-Swface Performance of High-Temperature Thermal Insulation, at the temper­ature to which they are exposed in service. In no case shall d1e test temperature be below 121 °C (250°F).

4.3.3.4 Air duct cove1·ings shall not extend through walls or floors that are required to be fire stopped or required to have a fire resistance rating, unless such coverings meet the require­ments of NFPA 80.

4.3.3.5* Air duct linings shall be interrupted at fire dampers to prevent interference with the operation of devices.

4.3.3.6 Air duct cove1-ings shall not be installed so as to conceal or prevent the use of any service opening.

4.3.3.7* \l\Tall or ceiling finish in plenums shall comply with 4.3.11.6.

4.3.4 Materials for Operation and Control of the Air Distribu­tion System.

4.3.4.1 * Wiring shall not be installed in air ducts, except as permitted in 4.3.4.2 through 4.3.4.4.

4.3.4.2 Wiring shall be permitted to be installed in air ducts only if the wiring is directly associated with the air distribution system and does not exceed 1.22 m ( 4 ft) .

4.3.4.3 Wiring permitted by 4.3.4.2 shall be as short as practi­cable.

4.3.4.4* Electrical wires and cables and optical fiber cables shall consist of wires or cables listed as having a maximum peak optical density of 0.50 or less, an average optical density of 0.15 or less, and a maximum flame spread distance of 1 .5 m (5 ft) or less when tested in accordance with NFPA 262 or shall be in­stalled in metal raceways without an overall nonmetallic cover­ing or metal sheathed cable without an overall nonmetallic covering.

4.3.4.5 Nonmetallic pneumatic tubing fix control systems shall be permitted to have up to 457.2 mm (18 in.) of tubing that meets the requirements of 4.3.1 1.2.6.2 to connect to equipment.

4.3.5 Air Duct Access and Inspection.

4.3.5.1 A service opening shall be provided in air ducts adjac cent to each fire damper, smoke damper, combination fire/ smoke damper, and any smoke detectors that need access for installation, cleaning, maintenance, inspection, and testing.

4.3.5.1.1 The opening shall be large enough to permit mainte­nance and resetting of the device.

2021 Edition

90A-10 INSTALLATION Or AJR-CONDITIONING AND VENTILATING SYSTEMS

4.3.5.2 Service openings shall be identified with letters having a minimum height of 12.7 mm (� in.) to indicate the location of the fire protection device (s) within.

4.3.5.3 Horizontal air ducts and plenums shall be provided with service openings to facilitate the removal of accumulations of dust and combustible materials.

4.3.5.3.1 Service openings shall be located at approximately 6.1 m (20 ft) intervals along the air duct and at the base of each vertical riser, unless othenvise permitted in 4.3.5.3.2 through 4.3.5.3.4.

4.3.5.3.2 Removable air outlet or air inlet devices of adequate size shall be permitted in lieu of service openings.

4.3.5.3.3 Service openings shall not be required in supply ducts where the supply air has previously passed through an air filter, an air cleaner, or a water spray.

4.3.5.3.4 Se1vice openings shall not be required where all the following conditions exist:

( 1 ) The occupancy has no process that produces combustible material such as dust, lint, or greasy vapors. Such occu­pancies include banks, office buildings, churches, hotels, and health care facilities (but not kitchens, laundries, and manufacturing portions of such facilities) .

(2) The air inlets are at least 2.13 m (7 ft) above the floor or are protected by corrosion-resistant metal screens of at least 1 4 mesh [1 .8 mm (0.07 in.)] that are installed at the inlets so that they cannot draw papers, refuse, or other combustible solids into the return air duct.

(3) The minimum design velocity in the return duct for the particular occupancy is 5.08 m/sec ( 1 000 ft/min).

4.3.5.4 Inspection windows shall be permitted in air ducts, provided they are glazed with wired or fire protection-rated glass.

4.3.5.5 Openings in walls or ceilings shall be provided so that service openings in air ducts are accessible for maintenance and inspection needs.

4.3.5.6 '.\'here a service opening is necessat)' in an air duct located above the ceiling of a floor-ceiling or a roof-ceiling assembly that has been tested and assigned a fire resistance rating in accordance with ASTM E 1 19, Standard 1est Methods for Fire Tests of Building Construction and Materials, or UL 263, Fire TesL5 of Building Construction and Materials, access shall be provi­ded in the ceiling.

4.3.5.7 The service opening shall be designed and installed so that it does not reduce the fire resistance rating of the assem­bly.

4.3.6 Air Duct Integrity.

4.3.6.1 Air ducts shall be located where they are not subject to damage 01- rupture, or they shall be protected to maintain their integrity.

4.3.6.2 �ere an air duct is located outdoors, the air duct, togethei- with its covering m lining, shall be protected from harmful element5.

4.3.6.3 '.\'here electrical, fossil fuel, or solar energy collection heat somces a1·e installed in ai1- ducts, the installation shall avoid the creation of a fire hazard.

2021 Edition

4.3.6.3.1 For air ducts rated as Cla5s 1 in accordance with UL 181, Fact1Jry-Made Air Ducts and Air Connectors, air duct cover­ings and linings shall be interrupted at the immediate area of operation of such heat sources in 4.3.5.3 in order to meet the clearances specified as a condition of the equipment listing, unless otherwise permitted in 4.3.5.3.2 or 4.3.5.3.3.

4.3.6.3.2 Appliances listed for zero clearance from combusti­bles shall be permitted to be installed in accordance with tl1e conditions of their listings.

4.3.6.3.3 Insulation specifically suited for the maximum temperature that reasonably can be anticipated on the duct surface shall be permitted to be in.stalled at the immediate area of operation of such appliances.

4.3.7 Air Outlets.

4.3.7.1 General. Air supplied to any space shall not contain flammable vapors, flyings, or dust in quantities and concentra­tions that would introduce a hazardous condition.

4.3.7.2 Construction of Air Outlets. Air outlets shall be constructed of noncombustible material or of a material that has a maximum flame spread index of 25 and a maximum smoke developed index of 50 when tested in accordance with ASTM E84, Standard Test Method for Swface Burning Characteris­tics of Building Mater ials, or UL 723, Test for Smface Burning Char­acteristics of Building Materials.

4.3.7.3 Location of Air Outlets.

4.3.7.3.1 Air outlets shall be located at least 76 mm (3 in.) above the floor, unless provisions have been made to prevent dirt and dust accumulations from entering the system.

4.3.7.3.2 Where located less than 2.13 m (7 ft) above the floor, outlet openings shall be protected by a grille or screen having openings through which a 12.7 mm (� in.) sphere cannot pass.

4.3.8 Air Inlets -Return or Exhaust or Return and Exhaust.

4.3.8.1 General. Air shall not be recirculated from any space in which f!anunable vapors, flyings, or dust are present in quan­tities and concentrations that would introduce a hazardous condition into the return air system.

4.3.8.2 Construction of Air Inlets. Ai1· inlets shall be construc­ted of noncombustible material or a material that has a maxi­mum flame spread index of 25 and a maximum smoke developed index of 50 when tested in accordance with ASTM E84, Standard Test Method for Smface Burning Characteristics of Building MateJials, or UL 723, Jest for Smface Burning Characteris­tics of Building Materials.

4.3.8.3 Location of Air Inlets.

4.3.8.3.1 Air inlets shall be located at least 76 mm (3 in.) above the flo01� unless provisions have been made to prevent dirt and dust accumulations from entering the system.

4.3.8.3.2 Where located less than 2.13 m (7 ft) above the floor, inlet openings shall be protected by a grille or screen having openings through which a 12.7 mm (� in.) sphere cannot pass.

4.3.9 Fire Dampers.

4.3.9.1 Approved fire dampers shall be provided as required in Chapter 5.

HVAC �YSTEMS 90A-ll

4.3.9.2 Approved fire dampers shall be installed in conform­ance with the conditions of their Listings.

4.3.10 Smoke Dampers.

4.3.10.l Approved smoke dampers shall be provided as 1-equired in Chapter 5.

4.3.10.1.1 Approved smoke dampers shall be installed in conformance with the conditions of their listings.

4.3.10.2 Smoke dampers shall be installed in systems with a capacity greater than 7080 L/sec ( 1 5,000 ft3/min) to isolate the air-handling equipment, including filters, from the remainder of the system on both the building supply side and the ren1rn side, in orde1- to restrict the circulation of smoke, unless specifi­cally exempted by4.3.10.2.l or 4.3.10.2.2.

4.3.10.2.1 Air-handling units located on the floor they serve and serving only that floor shall be exempt from the require­ments of4.3.10.2.

4.3.10.2.2 Air-handling unit5 located on the roof and serving only the floor immediately below the roof shall be exempt from the requirements of 4.3. 10.2.

4.3.ll Plenwns.

4.3.11.1 Storage.

4.3.11.1.1 Pl en urns shall not be used for occupancy or storage.

4.3.11.1.2 Accessible abandoned material shall be deemed to be in storage and shall be removed. "Where cables are identified for future use with a tag, the tag shall be of sufficient durability to withstand the environment involved.

4.3.11.2 Ceiling Cavity Plenum. The space benveen the top of the finished ceiling and the underside of the floor or roof above shall be permitted to be used to supply air to the occu­pied area or to return or exhaust air from the occupied area, provided that the conditions in 4.3. 1 1 .2.1 through 4.3.11.2.7 are met.

4.3.11.2.l The integrity of the fire and smoke stopping for peneo-ations shall be maintained.

4.3.11.2.2 Light diffusers, other than those made of metal or glass, used in air-handling luminaires shall be listed in accord­ance with UL 1598, Luminaires, and marked "Light Diffusers for Air-Handling Luminaires."

4.3.11.2.3 The temperanll"e of air delive1-ed to these plenums shall not exceed 121°C (250°F).

4.3.11.2.4 Materials used in the construction of a ceiling plenum shall be noncombustible or shall be limited combusti­ble having a maximum smoke developed index of 50, except as permitted in 4.3.11.2.4.1 through 4.3. 1 1 .2.4.3, and shall be suit­able for continuous exposure to the temperantre and humidity conditions of the environmental air in the plenum.

4.3.11.2.4.1 Materials used in the construction of a plemun space benveen the ceiling and roof (or floor) of other than the fire-resistive a5semblies covered in 5.3.3 shall be permitted as specified in 4.3.11 .2.4.2 and 4.3.11 .2.4.3.

4.3.11.2.4.2 The ceiling material shall have a flame spread index of not more than 25 and a smoke developed index not greater than 50. All surfaces, including those that would be

exposed by cutting through the material in any way, shall meet these requirements.

4.3.11.2.4.3 The ceiling materials shall be supported by noncombustible material.

4.3.11.2.5 Whe1-e the plenum is a part of a floor-ceiling m roof-ceiling assembly that has been tested or investigated and assigned a fire resistance rating of 1 hour or more, the assem­bly shall meet the requirement5 of 5.3.3.

4.3.11.2.6 Materials within a ceiling cavity plenum exposed to the airflow shall:

( 1 ) Be noncombustible, or (2) Exhibit a maximum flame spread index of 25 and a maxi­

mum smoke developed index of 50 when tested in accordance with ASTM E84, Standard Test Method for Surface Burning Cha:racte1istics of Bu ilding Mate1"ials, or with UL 723, Jest for Swface Burning Characte1"istics of Building Matel"iaLs, or

(3) Comply with 4.3.11.2.6.1 through 4.3.11.2.6. 1 1 , as appli­cable.

4.3.11.2.6.1 * Electrical wires and cables and optical fiber cables shall be listed as having a maximum peak optical density of 0.50 01- less, an average optical density of 0.15 or less, and a maximum flame spread distance of 1 .5 m (5 ft) or less when tested in accordance with NFPA 262 or shall be installed in metal raceways without an overall nonmetallic covering, metal sheathed cable without an overall nonmetallic covering, or totally enclosed nonventilated metallic busway without an over­all nonmetallic cove1·ing.

4.3.11.2.6.2 Pneumatic nibing for control systems shall be listed as having a maximum peak optical density of 0.5 or less, an average optical density of 0.15 or less, and a maximum flame spread distance of 1.5 m (5 ft) or less when tested in accordance with UL 1820, Fire Test of Pneumatic Tubing for Flame and Smoke Charactmistics.

4.3.11.2.6.3 Nonmetallic fire sprinkler piping shall be listed as having a maximum peak optical density of 0.5 or less, an aver­age optical density of 0.15 or less, and a maximum flame spread distance of 1 .5 m (5 ft) or less when tested in accord­ance with UL 1887, Fire Jest of Plastic Sp1inkler Pipe for Visible Flame and Smoke Characte1istics.

4.3.11.2.6.4 Communications raceways shall be listed as having a maximum peak optical density of0.50 or less, an aver­age optical density of 0.15 or less, and a maximum flame spread distance of 1 .5 m (5 ft) or less when tested in accord­ance with UL 2024, Cable Routing Assemblies and Communications Raceways.

4.3.11.2.6.5* Loudspeakers, recessed lighting fixntres, and other electrical equipment with combustible enclosures, including their assemblies and accessories, nonmetallic cable ties, wraps, nonmetallic cable supports, and other discrete products, shall be permitted in the ceiling cavity plenum where listed as having a maximwn peak optical density of 0.5 or less, an average optical density of 0.15 or less, and a peak heat release rate of 100 kW' or less when tested in accordance with UL 2043, Fire Test for Heat and Visible Smoke Release for Discrete Products and Their Accesso1ies Installed in Air-Handling Spaces.

4.3.11.2.6.6 Plastic piping and mbing used in plumbing systems shall be permitted to be used within a ceiling cavity plenum if it exhibits a flame spread index of 25 or less and a

2021 Edition

90A-12 INSTALLATION Or AJR-CONDITIONING AND VENTILATING SYSTEMS

smoke developed index of 50 or less when tested in accordance with ASTM E84, Standard Test Method for Su1face Burning Charac­teristics of Building Materials, or UL 723, 1est for Swface Burning Characteristics of Building Materials, at full width of the tunnel and with no water or any other liquid in the pipe during the test, unless permitted by4.3. l l .2.6.7.

4.3.11.2.6. 7 Plastic water distribution piping and tubing listed as having a maximum peak optical density of 0.5 or less, an average optical density of 0.15 or less, and a maximum flame spread distance of 1.5 m (5 ft) or less when tested in accord­ance with UL 2846, Fire 1"/Jst of Plastic Water Distribution Plumbing Pipe for Visible Flame and Smoke Characteristics, and installed in accordance with its listing, shall be permitted to be used within a ceiling cavity plenum.

4.3.11.2.6.8 Supplementary materials for air disU"ibution systems shall be permitted provided they comply with the provi­sions of 4.3.3.

4.3.11.2.6.9 Smoke detectors shall not be required to meet the provisions of Section 4.3.

4.3.11.2.6.10 Air ducts complying with 4.3.1.2 and air connec­tors complying with 4.3.2 shall be permitted.

4.3.11.2.6. ll Materials that, in the form in which they are used, shall have a potential heat value not exceeding 8141 kJ/kg (3500 Btu/lb) , when tested in accordance with NFPA 259 and include either of the following:

( 1 ) Materials having a structural base of noncombustible material, with a surfacing not exceeding a thickness of 3.2 mm (Ys in.) that has a flame spread index not g1-eater than 50.

(2) Materials, in the form and thickness used, having neither a flame spr·ead index greater drnn 25 nor evidence of continued progressive combustion, and of such composi­tion d1at surfaces that would be exposed by cutting through the material on any plane would have neither a flame spread index greater than 25 nor evidence of continued progressive combustion, when tested in accordance with ASTM E84, Standard 1est Method for Su1face Burning Characteristics of Building Mater ials, or UL 723, 1/>st for Sinface Burning Characteristics of Building Materials.

4.3.11.2. 7 The accessible portion of abandoned materials exposed to airflow shall be removed.

4.3.11.3 Apparatus Casing Plenum.

4.3.11.3.1 A fabricated plenum and apparams casing shall be permitted to be used for supply, remrn, or exhaust air service.

4.3.11.3.2 Fabricated plenum and apparatus casing shall be constructed of materials and by methods specified in 4.3.1 and in accordance with the following:

( 1 ) The casing and plenum consu·uction standards in SMACNA HVA C Duct Construction Standards - Metal and Flexible

(2) ASHRAE Handbook - HVAC Systems and Equipment (3) Subsection 4.3.3 for all air duct coverings, duct lining,

acoustical liner/cells, and miscellaneous materials

4.3.11.3.3 Elecu-ical wires and cables and optical fiber cables shall comply with 4.3.4.

2021 Edition

4.3.11.4 Air-Handling Unit Room Plenum.

4.3.11.4.1 * Individual rooms contammg an air-handling tmit(s) shall gad1er air from various sources and combine the air within the room before ren1rning it to the air-handling unit.

4.3.11.4.2 Duct covering, duct lining, acoustical line1·/ cells, and miscellaneous materials shall comply with 4.3.3.

4.3.11.4.3 Air-handling unit room plenums shall not be used for storage or occupancy other than during equipment servic­ing.

4.3.11.4.4 Accessible abandoned material shall be deemed to be in storage and shall be removed. v\lhere cables are identified for future use with a tag, the tag shall be of sufficient durability to withstand the environment involved.

4.3.11.4.5 Materials used in the construction of an air­handling unit room plenum shall be noncombustible or shall be limited combustible having a maximum smoke developed index of 50 and shall be suitable for continuous exposure to the temperature and humidity conditions of the environmental air in the plenum.

4.3.11.4.6* Elecu·ical wi1-es and cables and optical fiber cables shall be listed as having a maximum peak optical density of 0.50 or less, an average optical density of 0.15 or less, and a maximum flame spread distance of 1 .5 m (5 ft) or less when tested in accordance with NFPA 262 or shall be installed in metal raceways, metal sheathed cable, or totally enclosed nonventilated busway.

4.3.11.5 Raised Floor Plenum.

4.3.11.5.1 The space between the top of the finished floor and the underside of a raised floor shall be permitted to be used to supply air to the occupied area or remrn or exhaust air from or ren1rn and exhaust air from the occupied area, provided that the conditions in 4.3.11 .5.2 through 4.3. 1 1 .5.6 are met.

4.3.11.5.2 The integrity of the firestopping for peneu·ations shall be maintained.

4.3.11.5.3 The temperature of air delive1-ed to these plenums shall not exceed 121°C (250°F).

4.3.11.5.4 Materials used in the construction of a raised floor plenum shall be noncombustible or limited-combustible mate­rials, shall have a maximum peak smoke developed index of 50, and shall be suitable for continuous exposure to the tempera­ture and humidity conditions of the environmental ai1- in the plenum.

4.3.11.5.5 Materials within a raised floor plenum exposed to the airflow shall:

( l ) Be noncombustible, or (2) Exhibit a maximum flame spread index of 25 and a maxi­

mum smoke developed index of 50 when tested in accordance vvith ASTM E84, Standard 1est Method for Smface Burning Characteristics of Building Materials, or with UL 723, 1est for Smface Burning Characteristics of Building Materials, or

(3) Comply with 4.3.11.5.5.1 through 4.3.11.5.5.12, as appli­cable.

4.3.11.5.5.1 * Elecu-ical wires and cables and optical fiber cables shall be listed as having a maximum peak optical density of 0.50 or less, an average optical density of 0.15 or less, and a

HVAC �YSTEMS 90A-13

maximum flame spread distance of 1.5 m (5 ft) or less when tested in accordance with NFPA 262 01- shall be installed in metal raceways, metal sheathed cable, or totally enclosed nonventilated busway.

4.3.l 1.5.5.2 Pneumatic tubing for control systems shall be Listed as having a maximum peak optical density of 0.5 or less, an average optical density of 0.15 or less, and a maximum flame sp1-ead distance of 1 .5 m (5 ft) or less when tested in accordance with UL 1820, Fire Test of Pneumatic 71tbingfor Rame and Smoke Characteristics.

4.3.11.5.5.3 Nonmetallic fire sprinkler piping shall be listed as having a maximum peak optical density of 0.5 or less, an aver­age optical density of 0.15 or less, and a maximum flame spread distance of 1.5 m (5 ft) or less when tested in accord­ance with UL 1887, Fire Test of Plastic Sprinkler Pipe for Visib/,e Flame and Smoke Charactnistics.

4.3.11.5.5.4 Communications raceways shall be listed as having a maximum peak optical density of 0.50 or less, an aver­age optical density of 0.15 or less, and a maximum flame spread distance of 1.5 m (5 ft) or less when tested in accord­ance with UL 2024, Cable Routing Assemblies and Communications Raceways. Cables installed within these raceways shall be listed as plenum cable in accordance with the r·equirements in 4.3. 1 1 .5.5.1.

4.3.11.5.5.5 Raised floors, intermachine cables, electrical wit-es, listed plenum communications raceways, and optical­fiber cables in computer/data processing rooms where these rooms are designed and installed in accordance with NFPA 75 shall be permitted.

4.3.l 1.5.5.6 Loudspeakers, recessed lighting fixtures, and other electrical equipment with combustible enclosures, including their assemblies and accessories, nonmetallic cable ties, wraps, nonmetallic cable supports, and other discrete products, shall be permitted in the raised floor plenum where Listed as having a maximum peak optical density of 0.5 or less, an average optical density of 0.15 or less, and a peak heat release rate of 100 kW or less when tested in accordance with UL 2043, Fire Test for Heat and Visible Smoke Release far Discrete Products and Their Accessaries Installed in Air-Handling Spaces.

4.3.11.5.5. 7 Plastic piping and tubing used in plumbing systems shall be pennitted to be used within a rnised floor plenum if it exhibits a flame spread index of 25 or less and a smoke developed index of 50 or less when tested in accordance with ASTM E84, Standard Test Method for Smface Burning Charac­tni5tics of Building Matnials, or UL 723, Test for SU1face Burning Characte1i5tics of Building Mate1ials, at full width of the tunnel and with no water or any other liquid in the pipe during the test, unless otherwise permitted by 4.3.1 1.5.5.8.

4.3.11.5.5.8 Plastic water distribution piping and tubing listed as having a maximum peak optical density of 0.5 or less, an average optical density of 0.15 or less, and a maximum flame spread distance of 1.5 m (5 ft) or less when tested in accord­ance with UL 2846, Fire Test of Plastic Water Dist1ibution Plumbing Pipe for Visible Flf.lme and Smoke Characteii5tics, and installed in accordance with its listing, shall be permitted to be used within a raised floor plenum.

4.3.11.5.5.9 Air ducts complying with 4.3.1.2 and air connec­tors complying with 4.3.2 shall be permitted.

4.3.11.5.5.10 Materials, in the form in which they are used, shall have a potential heat value not exceeding 8141 kj/kg (3500 Btu/lb) when tested in accordance with NFPA 259 and include either of the following:

( 1 ) Materials having a strucmral base of noncombustible material, with a surfacing not exceeding a thickness of 3.2 mm (Ys in.) that has a flame spread index not greater than 50.

(2) Materials, in the form and thickness used, having neither a flame spread index greater than 25 no1- evidence of continued progressive combustion, and of such composi­tion that surfaces that would be exposed by cutting through the material on any plane would have neithe1- a flame spread index greater than 25 nor evidence of continued progressive combustion, when tested in accordance with ASTM E84, Standard Test Method for Smface Burning Charactnistics of Building Materials, or UL 723, ]est for SU1face Burning Characte1 i5tics of Building Mate?ials.

4.3.11.5.5.11 Smoke detectors shall not be required to meet the requirements of 4.3. 1 1 .5 .1 .

4.3.11.5.5.12 Supplementary materials for air distribution systems shall be permitted provided they comply with 4.3.3.

4.3.11.5.6 The accessible portion of abandoned materials exposed to airflow shall be removed. v\There cables are identi­fied for future use with a tag, the tag shall be of sufficient dura­bility to withstand the environment involved.

4. 3.11.6 Wall or Ceiling Finish in Pl en urns.

4.3.11.6.l Wall or ceiling finish in plenums, except as indica­ted in 4.3.11 .6.2, shall be noncombustible or shall exhibit a flame spread index of 25 01- less and a smoke developed index of 50 or less, when tested in accordance with ASTM E84, Stand­ard Test Method for SU1face Burning Characteii5tics of Building Mate­rials, or UL 723, Test for SU1face Burning Characte?i5tics of Building Mate1ials, at the maximum thickness intended for use.

4.3.11.6.2 Foam plastic insulation shall not be used as wall or ceiling finish in plenums unless the insulation meets any one of the criteria shown in 4.3.11.6.2.1 through 4.3.11 .6.2.4.

4.3.11.6.2.1 The foam plastic insulation material shall exhibit a flame sp1-ead index of 25 or less and a smoke developed index of 50 or less when tested in accordance with ASTM E84, Standard Test Method far Smface Burning Charactni5tics of Building Mate1ials, or UL 723, ]est for Surface Burning Characteristics of Building Materials, at the maximum thickness intended for use, and shall comply with the following criteria, when tested in accordance with NFPA 286 (whe1-e the testing shall be performed on the finished foam plastic assembly related to the acnial encl-use configuration and on the maximum thickness intended for use):

(1) Flame does not spread to the ceiling during the 40 kW exposure.

(2) Flame does not spread to the outer extremities of the sample.

(3) Flashove1-, based on the c1-iteria from NFPA 286, does not occur.

(4) The peak heat release rate does not exceed 800 kW. (5) The total smoke release does not exceed 1000 m2

(1 196 ycl2) .

2021 Edition

90A-14 INSTALLATION Or AJR-CONDITIONING AND VENTILATING SYSTEMS

4.3.11.6.2.2 The foam plastic insulation material shall be covered by corrosion-1-esistant steel having a base metal thick­ness of not less than 0.4 mm (0.0160 in.) and shall exhibit a flame spread index of 75 or less and a smoke developed index of 450 or less when tested in accordance with ASTM E84, Stand­ard Test Method for Smface Burning Characteristics of Building Mate­rials, or UL 723, Test for Swface Burning Charact,eristics of Building Materials, at the maximum thickness intended for use.

4.3.11.6.2.3 The foam plastic insulation material shall be sepa­rated from the plenum by an approved thermal barrier consist­ing of 12.7 mm (0.5 in.) gypsum wallboard or a material that is tested in accordance with and meets the acceptance criteria of both the temperature transmission fire test and the integrity fire test of NFPA 275 and shall exhibit a flame spread index of 75 or less and a smoke developed index of 450 or less when tested in accordance with ASTM E84, Standard Test Method for Surface Burning Characteristics of Building Materials, N UL 723, Test for Swface Burning Characteristics of Building Mater ials, at the maximum thickness intended for use.

4.3.ll.6.2.4 The foam plastic insulation material shall be sepa­rated from the plenum by not less than 25.4 mm ( 1 .0 in.) of masonry or concrete and shall exhibit a flame spread index of 75 or less and a smoke developed index of 450 or less when tested in accordance with ASTM E84, Standard Test Method for Surface Burning Characteristics of Building Materials, or UL 723, Test for Swface Burning Characteiistics of Building Mater ials, at the maximum thickness intended for use.

4.3.12 Corridor Air Systems.

4.3.12.1 Egress Corridors.

4.3.12.l.l* Egress corridors in health care, detention and correctional, and residential occupancies shall not be used as a portion of a supply, return, or exhaust air system serving adjoining areas unless otherwise permitted by 4.3.12.1.3. l through 4.3.12.1.3.4.

4.3.12.1.2 Air movement between rooms and egress corridors in hospitals, nursing facilities, and ambulatory care facilities shall be permitted where the transfer of air is required for clini­cal purposes by other standards.

4.3.12.l.3 An air transfer open.ing(s) shall not be permitted in walls or in doors separating egress corridors from adjoining areas.

4.3.12.l.3.1 An air transfer open.ing(s) shall be permitted in walls or doors from toilet rooms, bathrooms, shower rooms, sink closets, and similar auxiliary spaces opening directly onto the egress corridor.

4.3.12.l.3.2 Where door clearances do not exceed those speci­fied fo1- fire doors in NFPA 80 air transfer caused by pressure differentials shall be permitted.

4.3.12.1.3.3 Use of egress corridors shall be permitted as part of an engineered smoke-control system.

4.3.12.l.3.4 Air o-ansfer opening(s) shall be permitted in walls or in doors separating egress corridors from adjoining areas in detention and correctional occupancies with corridor separa­tions of open construction (e.g., grating doors or grating parti­tions).

2021 Edition

4.3.12.2 Exits. Exit passageways, stairs, ramps, and other exits shall not be used as a part of a supply, return, 01- exhaust air system serving other areas of the building.

4.3.13* Smoke Control. Where a smoke-control or exhaust system is required, it shall conform to the requirements of the building code of the authority havingjurisdiction.

4.4 Materials.

4.4.1 * Noncombustible Material.

4.4.1.l A material that complies with any of the following shall be considered a noncombustible material:

(1) A material that, in the form in which it is used and under the conditions anticipated, will not ignite, burn, support combustion, or release flammable vapo1-s when subjected to fire or heat

(2) A material that is reported as passing ASTM El36, Stand­ard Test Method for Behavior of Materials in a Vertical Tube Furnace at 750°C

(3) A material that is reported as complying with the pass/fail criteria of ASTM E l 36 when tested in accordance with the test method and procedure in ASTM E2652, Standard 11'.st Method for Behavior of Material5 in a Tube Furnace with a Qme-Shaped Ai1jlow Stabilizer, at 750°C

[I 01:4.6.13. I]

4.4.1.2 Where the term limited-combustible is used in this stand­ard, it shall also include the term noncombustible. [101:4.6.13.2]

4.4.2 Limited-Combustible Material. A material shall be considered a limited-combustible material where one of tl1e following is met:

( 1 ) The conditions of 4.4.2.1 and 4.4.2.2, and the conditions of either 4.4.2.3 or 4.4.2.4, shall be met.

(2) The conditions of 4.4.2.5 shall be met. [I 01:4.6.14]

4.4.2.1 The material shall not comply with the requirements for noncombustible material in accordance with 4.4.l . r 101:4.6.14.1J

4.4.2.2 The material, in the fo1-m in which it is used, shall exhibit a potential heat value not exceeding 3500 Btu/lb (8141 kJ/kg) where tested in accordance with NFPA 259. [101:4.6.14.2]

4.4.2.3 The material shall have the strucn1ral base of a noncombustible material with a surfacing not exceeding a thickness of Ys in. (3.2 mm) where the surfacing exhibits a flame spread index not greater than 50 when tested in accord­ance with ASTM E84, Standard Test Method for Swface Burning Characteristics of Building Materials, or UL 723, Test for Swface Burning Characteristics of Building Materials. f 101:4.6. 14.3 l

4.4.2.4 The material shall be composed of materials that, in the form and thickness used, neither exhibit a flame spread index greater than 25 nor evidence of continued progressive combustion when tested in accordance with ASTM E84, Stand­ard Test Method for Swf ace Burning Characteii5tics of Building Ma� r ials, or UL 723, Jest for Smface Burning Characteristics of Building Materials, and shall be of such composition that all surfaces tl1at would be exposed by cutting through the material on any plane would neither exhibit a flame spread index g1-eater than 25 no1-exhibit evidence of continued progressive combustion when tested in accordance witl1 ASTM E84 or UL 723. [101:4.6.14.4]

INTEGRATION OF A \IENTLLATION AND AlR-CONDITIONING SYSTEM (S) WITH BUILDING CONSTRUCTION 90A-15

4.4.2.5 Materials shall be considered limited-combustible materials where tested in accordance with ASTM E2965, Stand­ard Test Method for Determination of Low Levels of Heat Rel.ease Rate for Materials and Products Using an Oxygen Consumption Calorime­ter, at an incident heat flux of 75 kW/m2 for a 20-minute expo­sure and both of the following conditions are met:

( 1 ) The peak heat release rate shall not exceed 150 kW/m2

fo1- longer than 10 seconds. (2) The total heat released shall not exceed 8 MJ/ m2. [101:4.6. 14.51

4.4.2.6 V.lhere the term limited-comlni,stibl.e is used in this stand­ard, it shall also include the term noncombustibl.e. [101:4.6.14.6)

Chapter 5 Integration of a Ventilation and Air-Conditioning System(s) with Building Construction

5.1 Air-Handling Equipment Rooms.

5.1.1 General. Air-handling equipment rooms shall be classi­fied into the following three categories:

( 1 ) Those used as air plenums (usually return air) (2) Those with air ducts that open directly into a shaft (3) Other air-handling unit rooms

5.1.2 Air-Handling Equipment Rooms Used as Plenum Space. Air-handling equipment rooms used as plenums for supply or 1-en1rn air shall comply with 4.3.1 1.4.

5.1.3 Air-Handling Equipment Rooms That Have Air Ducts That Open Directly into a Shaft.

5.1.3.l Air-handling equipment rooms, including the protec­tion of openings, shall be separated from shafts by construction having a fire resistance rating not less than that required for the shaft by 5.3.4.

5.1.3.2 Fire-resistant separation shall not be required for air­handling equipment rooms that are enclosed by construction having a fire 1-esistance rating not less than that required for the shaft.

5.1.4 Other Spaces Housing Air-Handling Units. Other spaces housing air-handling units shall meet the requirements of the building code of the authority havingjurisdiction.

5.2 Building Construction.

5.2.1 Air Duct Clearance.

5.2.1.1 The clearance from metal air ducts used for heating to assemblies constructed of combustible materials, including plaster on wood lath, shall be not less tlwn 12.7 mm (Y.i in.), or the combustible material shall be protected with minimum 6.35 mm (!i.t in.) thick approved insulating material .

5.2.1.2 The integ1-ity of the firestopping and smokestopping shall be maintained.

5.2.1.3 The clearances provided in 5.2. l . I shall not apply to systems used solely for ventilation, air cooling, or air condition­ing without heating.

5.2.2 Structural Members. The installation of air duct5, including the hangers, shall not reduce the fire resistance rating of sn-ucrural members.

5.2.3 Ceiling Assemblies. Where the installation of the hang­ers for the components of an air duct system peneu-ates an

eXJstmg ceiling of a fire-resistive floor-ceiling or roof-ceiling assembly and necessitates removal of a portion of that ceiling, the replacement material shall be identical to that which was removed or shall be approved as equivalent to that which was removed.

5.2.4 As an alternative to repairing the existing ceiling, a new ceiling shall be permitted to be installed below the air duct system, provided the fit-e resistance rating of the floor-ceiling or roof-ceiling design is not reduced.

5.3* Penetrations - Protection of Openings.

5.3.1 Fire-Rated Walls and Partitions.

5.3.1.1 * Approved fire dampers shall be provided where air ducts penetrate or terminate at openings in walls or partitions requi1-ed to have a fire resistance rating of 2 hours 01- more.

5.3.1.1.1* Fire dampers shall not be required where other openings through the wall are not required to be protected.

5.3.1.2 Approved fire dampers shall be provided in all ai1-0"ansfer openings in partitions tl1at are required to have a fire resistance rating and in which other openings are required to be protected.

5.3.2 Floors Required to Have a Fire Resistance Rating.

5.3.2.1 Where air ducts extend through only one floor and serve only two adjacent stories, tl1e air ducts shall be enclosed (see 5.3.4.1), or fire dampers shall be installed at each point where the floor is penetrated.

5.3.3* Floor-Ceiling or Roof-Ceiling Assemblies Having a Fire Resistance Rating.

5.3.3.1 Where air ducts and openings for air ducts are used in a floor-ceiling 01- roof�ceiling assembly that is required to have a fire resistance rating, all the materials and tl1e consO"Uction of the assembly, including the air duct materials and the size and protection of the openings, shall conform with the design of the fire-resistive assembly, as tested in accordance with ASTM E l 19, Standard Jest Methods for Fire Tests of Building Construction and Materials, or UL 263, Fire Tests of Building Construction and Materials.

5.3.3.2 Where dampers are required, they shall be located in accordance with 5.4.4.

5.3.4 Shafts.

5.3.4.1 Air ducts that pass through the floors of buildings that requi1-e the protection of vertical openings shall be enclosed with partitions or walls constructed of materials as permitted by the bui !ding code of the authority having jurisdiction, as indi­cated in 5.3.4.2 or 5.3.4.3, unless otherwise permitted by 5.3.4.3 . l .

5.3.4.2 The shaft enclosure shall have a minimtu11 fire resist­ance rating (based on possible fire exposure from either side of the partition or wall) of 1 hour where such air ducts are located in a building less than four stories in height.

5.3.4.3 The shaft enclosure shall have a minimum fit-e resist­ance rating (based on possible fire exposure from either side of the partition or wall) of 2 hours where such air duct5 are locac ted in a building four stories or more in height.

2021 Edition

90A-16 INSTALLATION Or AJR-CONDITIONING AND VENTILATING SYSTEMS

5.3.4.3.1 Where an air duct penetrates only one floor or one floor and an air-handling equipment penthouse floor, and the air duct contains a fire damper located where the duct pene­trates the floor, an air duct enclosure shall not be required.

5.3.4.4 A fire-resistive enclosure used as an air duct shall conform with 4.3.1 and with 5.3.4.2 through 5.3.4.3. l .

5.3.4.4.1 Gypsum board systems shall be constructed in accordance with GA-600, Fi:re Resistance Design Manual.

5.3.4.5 Shafts that constitute air ducts or that enclose air ducts used for the movement of environmental air shall not enclose the following:

( 1) Exhaust ducts used for the removal of smoke- and grease­laden vapo1·s from cooking equipment

(2) Ducts used for the removal of flammable vapors (3) Ducts used for moving, conveying, or transporting stock,

vapor, or dust ( 4) Ducts used for the removal of nonflammable corrosive

fumes and vapors (5) Refuse and linen chutes (6) Piping, except for noncombustible ptpmg conveying

water or other nonhazardous or nontoxic materials (7) Combustible storage

5.3.4.6 Fire dampers shall be installed at each direct or ducted opening into and out of enclosures required by 5.3.4. 1 , unless otherwise permitted by 5.3.4.6.1 01· 5.3.4.6.2.

5.3.4.6.1 A fire clamper shall not be required where an air duct system serving only one story is used only for exhaust of air to the outside and is contained within its own dedicated shaft.

5.3.4.6.2 A fire damper shall not be required where the follow­ing conditions exist:

( 1 ) Branch ducts connect to enclosed exhaust risers meeting the requirements of 5.3.4.1 or 5.3.4.4.

(2) The airflow moves upward. (3) Steel subducts at least 560 mm (22 in.) in length are

carried up inside the riser from each inlet. ( 4) The riser is appropriately sized to accommodate the flow

restriction created by the subduct.

5.3.5 Smoke Barriers.

5.3.5.1 Smoke dampers shall be installed at or adjacent to the point where air ducts pass through required smoke barriers, but in no case shall a smoke damper be installed more than 0.6 m (2 ft) from the barrier or after the first air duct inlet or outlet, whichever is closer to the smoke barrier, unless other­wise permitted by 5.3.5 . 1 . 1 through 5.3.5.1.5.

5.3.5.1.1 Smoke dampers shall not be required on air systems other than where necessary for the proper functioning of that system where the system is designed specifically to accomplish the following:

( 1 ) Function as an engineered smoke-control system, includ­ing the provision of continuous air movement \'/itl1 the air-handling system

(2) Provide air to other areas of the building during a fire emergency

(3) Provide pressure differentials during a fire emergency

5.3.5.1.2 Smoke dampers shall not be 1·equired to be located within a prescribed distance of a smoke barrier where isolation

2021 Edition

smoke dampers complying with 4.3.9.2 are used in air-handling equipment.

5.3.5.1.3 Smoke dampers shall not be required where the air inlet or outlet openings in ducts are limited to a single smoke companment.

5.3.5.1.4 Smoke dampers shall not be required in ducts where the air continues to move and the air-handling system installed is arranged to prevent recirculation of exhaust or renirn au· Lmder fire emergency conditions.

5.3.5.1.5* Smoke dampers shall not be required in occupan­cies where exempted by NFPA 101 or NFPA 5000.

5.3.5.2 '"'here peneo-ation of a smoke barrier is required to be provided with a fire damper, a combination fire and smoke damper equipped and arrnnged to be both smoke responsive and heat responsive shall be permitted.

5.4 Fire Dampers, Smoke Dampers, and Ceiling Dampers.

5.4.l Fire Dampers.

5.4.1.1 Fire dampers used for the protection of openings in walls, partitions, or floors with fire resistance ratings of less tl1an 3 homs shall have a 1 Yrhour fire protection rating in accordance with UL 555, Fire Darnpers.

5.4.2 Fire dampers used for the protection of openings in walls, partitions, or floors having a fire resistance rating of 3 hours or more shall have a 3-hour fire protection rating in accordance with UL 555, Fire Darnpers.

5.4.3* Smoke Dampers. Smoke dampers used for the protec­tion of openings in smoke barriers or in engineered smoke­control systems shall be classified in accordance with UL 555S, Srnoke Darnpers.

5.4.3.1 Smoke clamper leakage ratings shall meet, as a mini­mum, Class II, and elevated tempernnire ratings shall be not less than 121 °C (250°F).

5.4.4 Ceiling Dampers.

5.4.4.1 * Ceiling dampers or other methods of protecting openings in rated floor-ceiling or roof�ceiling assemblies shall comply with the construction details of the tested floor-ceiling 01· roof-ceiling assembly or with listed ceiling air diffusers 01-listed ceiling dampers.

5.4.4.2 Ceiling dampers shall be tested in accordance \'lith UL 555C, Ceiling Darnpers.

5.4.5 Damper Closure.

5.4.5.1 All fire dampers and ceiling dampers shall close auto­matically.

5.4.5.1.1 All fire dampers and ceiling dampers shall remain closed upon the operation of a listed fusible link or other approved heat-actuated device located where it will be readily affected by an abnormal rise of temperature.

5.4.5.2 Fusible Links.

5.4.5.2.1 Fusible links shall have a temperanire rating approxi­mately 28°C (50°F) above the maximum temperanire tl1at normally is encountered when the system is in operation or shut down.

CONTROLS

5.4.5.2.2 Fusible links shall have a temperature rating not less than 71°C ( 1 6Q°F).

5.4.5.2.2.1 ':' V\fhere combination fire and smoke dampers are located within air ducts that are part of an engineered smoke­control system, fusible links or other approved heat-responsive devices shall have a temperature rating approximately 28°C (50°F) above the maximum smoke-control system designed operating temperature.

5.4.5.2.2.2 The combination fire and smoke dampers shall not exceed the UL 555S, Smoke Dampers, degradation test tempera­ture rating of the combination fire and smoke damper.

5.4.5.2.2.3 The combination fire and smoke dampers shall not exceed a maximum temperature rating of l 77°C (350°F).

5.4.5.3 A provision for remote opening of combination fire and smoke dampers, where necessary for smoke removal, shall be permitted.

5.4.5.3.l Combination fit·e and smoke dampers permitted in 5.4.5.3 shall have provisions that allow them to reclose automat­ically upon reaching the damper's maximum degradation test temperature in accordance with UL 555S, Smoke Dampers.

5.4.5.4* Dampers shall close against the maximum calculated airflow of that portion of the air duct system in which they are installed.

5.4.5.4.1 Fire dampers shall be tested for closure in accord­ance with UL 555, Fire Dampers.

5.4.5.4.2 Smoke dampers shall be tested fo1- closure in accord­ance with UL 555S, Smoke Dampers.

5.4.5.4.3 Fire dampers, smoke dampers, and combination fi1·e/smoke dampers shall not be required in ducts used for kitchen or clothes dryer exhaust systems.

5.4.6 Damper Location Information.

5.4.6.1 The locations and mounting arrangement of all fire dampers, smoke dampers, ceiling dampers, and fire protection means of a similar nature required by this standard shall be shown on the drawings of the air duct systems.

5.4.6.2 Dampers required to close in airflow shall have the calculated airflow at their location shown on the drawings of the air duct system.

5.4.7 Installation.

5.4.7.1 * Fire dampers, including their sleeves; smoke damp­ers; and ceiling dampers shall be installed in accordance with the conditions of their listings and the manufacturer's installa­tion instructions and the requirements of NFPA 80.

5.4.7.2 Smoke dampers shall be installed in accordance with the conditions of their listings, the manufacturer's installation insn·uctions, and the requirements ofNFPA 105.

5.4.8 Maintenance.

5.4.8.1 Fire dampers and ceiling dampers shall be maintained in accordance with NFPA 80.

5.4.8.2 Smoke dampers shall be maintained in accordance with NFPA 105.

90A-l 7

Chapter 6 Controls

6.1 Wiring. The installation of electrical wmng and equip­ment associated with the operation and control of air­conditioning and ventilating systems shall be in accordance with NFPA 70.

6.2 Manual Control.

6.2.l Each air disn·ibution system shall be provided with at least one manually operable means for stopping the operation of the supply, return, and exhaust fan (s) in an emergency.

6.2.2 The means of manual operation shall be located at an approved location.

6.3* Smoke Dampers.

6.3.1 Smoke dampers shall be conn·olled by an automatic alarm-initiated device.

6.3.2* Smoke dampers shall be permitted to be positioned manually from a command station.

6.3.3 Smoke dampers installed to isolate the air-handling system in accordance with 4.3.10.2 shall be arranged to close automatically when the system is not in operation.

6.3.4* Smoke dampers shall be permitted to remain open when their associated fan is off, provided their associated controlling damper acniators and automatic alann-initiating devices remain operational .

6.4* Smoke Detection for Automatic Control.

6.4.1 Testing. All automatic shutdown devices shall be tested at least annually.

6.4.2* Location.

6.4.2.1 Smoke detectors listed for use in air distribution systems shall be located as follows:

(1) Downstream of the air filters and ahead of any branch connections in air supply systems having a capacity greater than 944 L/sec (2000 ft3/min)

(2) At each story prior to the connection to a common ren1rn and prior to any recirculation or fresh air inlet connec­tion in air return systems having a capacity greater than 7080 L/sec ( 1 5,000 ft3/min) and serving more than one story

6.4.2.2 Return system smoke detectors shall not be required where the entire space served by the air distribution system is protected by a system of area smoke detectors.

6.4.2.3 Smoke detectors shall not be required for fan units whose sole function is to remove air from the inside of the building to the outside of the building.

6.4.3* Function.

6.4.3.1 Smoke detectors provided as required by 6.4.2 shall automatically de-energize their respective fans upon detecting the presence of smoke.

6.4.3.2 Where the ren1rn air fan is functioning as pan of an engineered smoke-control system and a different mode is required, the smoke detectors shall not be required to auto­matically stop their respective fans.

2021 Edition

90A-18 INSTALLATION Or AJR-CONDITIONING AND VENTILATING SYSTEMS

6.4.4 Installation.

6.4.4.l Smoke detectors shall be installed, tested, and main­tained in accordance with NFPA 72.

6.4.4.2 In addition to the requirements of 6.4.3, where an approved fire alann system is installed in a building, the smoke detectors required by the provisions of Section 6.4 shall be connected to the fire alarm system in accordance with the 1·equirements of NFPA 72.

6.4.4.2.l Smoke detectors used solely for closing dampers or for heating, ventilating, and air-conditioning system shutdown shall not be required to activate the building evacuation alarm.

6.4.4.3 V\There smoke detectors required by Section 6.4 are installed in a building not equipped with an approved fire alarm system as specified by 6.4.4.2, the following shall occur:

( 1 ) Smoke detector activation required by Section 6 . 4 shall cause a visual signal and an audible signal in a n01·mally occupied area.

(2) Smoke detector n·ouble conditions shall be indicated visually or audibly in a normally occupied area and shall be identified as air duct detector trouble.

6.4.4.4 Smoke detectors powered separately from the fire alarm system for the sole function of stopping fans shall not require standby power.

Chapter 7 Acceptance Testing

7.1 General.

7.1.l* An acceptance test shall be perfo1·med to determine that the protective measures required in this standard function when needed in order to restrict the spread of fire and smoke.

7.1.2 Records shall be maintained on acceptance test results.

7.1.2.1 Records shall be available for inspection.

7 .2* Fire Dampers, Smoke Dampers, and Ceiling Dampers. All fi1·e dampers, smoke dampers, and ceiling dampers shall be operated prior to the occupancy of a building to determine that they function in accordance with the requirements of this standard.

7.2.l Access. Dampers equipped with fusible links, internal operators, or both shall be provided with an access door that is not less than 12 in. (305 mm) square or provided with a 1·emov­able duct section.

7.2.2 Access shall not be obsn·ucted.

7.2.3 Testing.

7.2.3.1 All fire dampers, smoke dampers, and ceiling dampers shall be tested to determine their proper functioning in accordance with the requirements of this standard prior to the occupancy of the building.

7.2.3.2 The operational test shall verify that there is full and unobstructed access to the fit·e damper and all listed compo­nents. [80:19.3.1.51

7.3 Controls and Operating Systems.

7.3.1 * Conn·ols required by Chapter 6 shall be tested for compliance with the requirements of this standard.

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7.3.2 Acceptance tests of fire protection devices in air­conditioning and ventilating systems shall, as far as practicable, be performed under normal operating conditions.

7.3.3 Portions of control or alarm systems are permitted to have standby power or od1er emergency modes of operation.

7.3.4 The tests shall be performed to determine that the system operates under d1e standby power or emergency opera­tion mode conditions as well as under normal conditions.

Annex A Explanatory Material

Annex A is not a part of the requirements of this NFPA document but is included fm· informational pmposes only. 17iis annex contains explan­at01y material, numbered to c01Tespond with the applicable text para­graphs.

A.I.I An air duct system has the potential to convey smoke, hot gases, and flame from area to area and to supply air to aid combustion in the fire area. For these reasons, fire protection of an air duct system is essential to safety to life and the protec­tion of property. However, an air duct system's fire integrity also enables it to be used as part of a building's fire protection system.

Guidance for the design of smoke-control systems is provi­ded in NFPA 92.

Pertinent information on maintenance is provided in Annex B.

Maintenance of fire dampers, ceiling dampers, smoke damp­ers, and combination fire/smoke dampers requirements can be found in NFPA 80 and NFPA 105.

A.1.3(1) For the purposes of this standard, a space is consid­ered as an entire building or a portion thereof separated from all oilier portions of me building by fire resistance-rated consn·uction and whose environmental air does not mix with that of any other space. [For spaces not exceeding 708 m3 (25,000 jt!) in volume, see NFPA 90B.J

A.1.3(2) For consn-t1ction types, see NFPA 220.

A.1.3(3) Such applicable standards include, but are not limi­ted to, NFPA 70 (see Ventilation in index) and NFPA 90B.

A.1.3(4) Such applicable standards include, but are not lin1i­ted to, NFPA 31, NFPA 33, NFPA 34, NFPA 45, NFPA 70 (see Ventilation in index), NFPA 75, NFPA 9 1 , and NFPA 96.

A.3.2.1 Approved. The National Fire Protection A�sociation does not approve, inspect, or certify any installations, proce­dures, equipment, or materials; nor does it approve or evaluate testing laboratories. In determining the acceptability of installa­tions, procedures, equipment, or materials, the auiliority having jurisdiction may base acceptance on compliance with NFPA or other appropl"iate standards. In the absence of such standards, said auiliority may require evidence of proper instal­lation, procedure, or use. The authority having jurisdiction may also refer to the listings or labeling practices of an 01·gani­zation that is concerned wid1 product evaluations and is d1us in a position to determine compliance with appropriate standards fo1· the current production of 1 isted items.

ANNEX A

A.3.2.2 Authority Having Jurisdiction (AHJ). The phrase "authority having jurisdiction," or its acronym AH], is used in NFPA documents in a broad manner, since jurisdictions and approval agencies vary, as do their responsibilities. Where public safety is primary, the authority having jurisdiction may be a federal, state, local, or other regional department or individual such as a fire chief; fire marshal; chief of a fire prevention bureau, labor deparunent, or health deparunent; building official; electrical inspector; or others having statutory authority. For insurance purposes, an insurance inspection deparunent, rnting bureau, or other insurance company repi-e­sentative may be the authority having jurisdiction. In many circumstances, the property owner or his or her designated agent assumes the role of the authoi-ity having jurisdiction; at government installations, the commanding officer or depart­mental official may be the authority havingjurisdiction.

A.3.2.3 Listed. The means for identifying listed equipment may vary for each organization concerned with product evalua­tion; some organizations do not recognize equipment as listed tmless it is also labeled. The authority having jurisdiction should utilize the system employed by the listing organization to identify a listed product.

A.3.3.3 Air Connector. Some such devices are listed in UL Heating, Cooling, Ventilating and Cooking Equipment Directory under the category "Connectors (ALNR)." Because these devi­ces do not meet all the requirements for air ducts, they have limitations on their use, length, and location. (For limitations on the use of air connecto rs, see 4.3.2.1.)

A.3.3.9 Air Inlet. For further discussion of various types of air inlet devices, see Chapter 20, "Space Air Diffusion," in the 2013 edition of ASHRAE Handbook - Fundamentals.

A.3.3.10 Air Outlet. For farther discussion of various types of air outlet devices, see ASHRAE Handbook - Fundamentals, Chapter 32, "Space Air Diffusion."

A.3.3.14.l Ceiling Damper. Some such devices ai-e listed in UL Fire Resistance Directmy under the category "Ceiling Damper (CABS)."

A.3.3.14.3 Fire Damper. Some such devices are listed in UL Heating, Cooling, Ventilating and Cooking Equipment Directory under the category of "Fire Dampers for Fire Barrier and Smoke Applications (EMME)." Fire dampei-s are classified for use in either static systems or for dynamic systems, where the dampers are rated for closure under airflow.

A.3.3.14.4 Smoke Damper. Smoke dampers are subjected to various pressure differentials, are exposed to elevated tempera­tures, and can be required to open or close against mechani­cally induced airflow. Some such devices are listed in UL Heating, Cooling, Ventilating and Cooking Equipment Directory under the category "Dampers for Fire Barrier and Smoke Applications (EMME)."

A.3.3.17 Fire Resistance Rating. Some such assemblies are listed in UL Fire Resistance Directory under the categories "Floors," "Roofs," and "\i\lalls and Partitions."

A.3.3.19 Flame Spread Index. Flame spread indexes for some materials are listed in UL Building Materials Directary. Classifica­tions have been developed using flame spread index values.

A.3.3.21 Limited-Combustible (Material). Material subject to increase in combustibility or flame spread index beyond the limits hei-ein established through the effects of age, moisture,

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or other atmospheric condition is considered combustible. (See NFPA 25 9 and NFPA 220.)

A.3.3.22 Noncombustible Material. A material that is repor­ted as complying with the pass/fail criteria of ASTM E l 36, Standard Test Method for Behavior of Materials in a Vertical Tube Furnace at 750°C, when tested in accordance with d1e test method and procedure in ASTM E2652, Standard Test Method for Behavior of Materials in a Tube Furnace with a Cane-Shaped Ai1flow Stabilizer, at 750°C, is considered a noncombustible material .

A.3.3.23 Plenum. A plenum can be one of the following five described types of unoccupied chambers through which air flows at low velocity and with little change in static pressure:

( 1 ) Supply air plenum. Any plenum at any point on the discharge side of a fan through which air is intentionally conveyed to a space or spaces within a building.

(2) Return air plenum. Any plenum at any point on the intake side of a fan through which air is intentionally conveyed from a space or spaces within the building to the fan for eventual complete or partial retun1 to the same space 01-spaces.

(3) Exhaust air plenum. Any plenum at any point on the intake side of a fan through which air is intentionally removed from a space or spaces within the building for discharge to the exterior of the building.

(4) Outside air plenum. Any plenum at any point on the intake side of a fan mrough which air from me exterior of me building is intentionally introduced into the building or its ventilation system(s).

(5) Mixed-air plenum. Any plenum at any point on me intake side of a fan through which air is intentionally conveyed from a space or spaces within the building and from the exterior of d1e building to the fan for eventual complete or partial return to the same space or spaces.

A.3.3.25 Smoke Barrier. A smoke barrier might be vei-tically or horizontally aligned, such as a wall, floor, or ceiling assem­bly. A smoke barrier might or might not have a fire resistance rating. (See Chapter 8 of NFPA 1 OJ for additional guidance.)

A.3.3.27 Smoke Detector. See NFPA 72.

A.3.3.28 Smoke Developed Index. Smoke developed indexes for some materials are listed in UL Building Materials Directory. Classifications have been developed using smoke developed index values.

A..4.2.1.2 The location of out5ide air intakes, including intakes located on roofs, needs to be carefully selected to avoid draw­ing in objectionable materials, including, but not limited to, combustible materials and toxic or hazardous vapors. The loca­tion should consider proximity to emergency smoke exhaust, garage exhaust, discharge of kitchen hood vents, and other objectionable discharges from the building or adjacent strnc­tures.

A.4.2.2.2 For care and maintenance, see Annex B.

A.4.3 Abandoned wires, cables, and other building service materials exposed to airflow result in an unnecessary increase in ti.tel load. \.\There practical, installation locations and meth­ods that anticipate and facilitate the 1-emoval of such materials should be selected.

A.4.3.3.1 ASTM E223 1 , Standard Practice for Specimen Prepara­tion and Maunting of Pipe and Duct Insulation Materials to AsseS5 Surface Burning Characteristics, is a practice that describes, in

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90A-20 INSTALLATION Or AJR-CONDITIONING AND VENTILATING SYSTEMS

mandatory language, standard methods for specimen prepara­tion and mounting of pipe and duct insulation systems using the Steiner tunnel test method (contained in ASTM E84, Stand­ard Test Method for SU1face Burning Characteristics of Building Mate­rials). It requires that the entire system that is used in the field be tested, including the insulation itself, any adhesive, and/or any jacket used. The practice recognizes that pipe or duct insu­lation systems can comprise a single product or of a combina­tion of products, and that these systems have a variety of physical characteristics, including that they might or might not be self-supporting.

A.4.3.3.5 See NAIMA Fibrous Glass Duct Liner Standard and NAIMA Fibrous Glass Duct Construction Standards for additional information.

A.4.3.3. 7 It is the intent of the committee that wall and ceiling finish in ceiling plenums comply with 4.3.3.7 and not 4.3.3.1.

A.4.3.4.1 Access doors for fit-e dampers should be located so that the spring catch and fusible links are accessible when the damper is closed. v\There the size of the duct permits, the mini­mum access door size should be 457 mm x 406 mm ( 1 8 in. x

16 in.). For dampers that are too large for an ordinary person's arms to reach from outside the duct to reset the damper and 1-eplace d1e fusible link, the minimum size for the access door should be increased to 610 mm x 406 mm (24 in. x 16 in.) to allow the entrance of an individual.

Access doors should be located as close as practicable to fire dampers and smoke dampers. If feasible, the underside of the duct should be used rather than a side door.

Many fire dampers and smoke dampers are preloaded with powerful springs that force the damper to shut. These dampers need to be opened against these springs, which could necessi­tate the ability to get two arms into the duct.

A.4.3.4.4 Electrical wires and cables and optical fiber cables instal.led in metal raceways or metal sheathed cable are not considered to be exposed to the airflow and need not meet the requirements of 4.3.4.4. Electrical wires and cables and optical fiber cables listed to UL 2424, Outline of Investigation for Cable Marked 'Limited Combustible,' are conside1-ed to be suitable for use wherever cables tested in accordance with NFPA 262 are required.

A.4.3.11.2.6.1 Elecu-ical wires and cables and optical fiber cables listed to UL 2424, Outline of Investigation /<Jr Cable Marked 'Limited C<Jmbt1Stible', are considered to be suitable for use wher­ever cables tested in accordance with NFPA 262 are required.

A.4.3.11.2.6.5 Nonmetallic cable ties listed to UL 62275, Cable Management Systems - Cable Ties for Elect1ical Installations, and nonmetallic cable supports listed to UL 1565, Positioning Devi­ces, and marked for use in plenums are considered suitable for use wherever nonmetallic cable ties or nonmetallic cable suppo1-ts tested in accordance with UL 2043, Fire Test for Heat and Visible Smoke &l£r1Se f<Jr Discrete Products and Their Accessories Installed in Air-Handling Spaces, are required.

A.4.3.11.4.1 It is not the intent of this section to apply to a room containing an air handler with a single source of return into the room, where the air from various sources is combined outside of the air-handling unit's room (e.g., as in apartment unit5).

A.4.3.11.4.6 Elecu-ical wires and cables and optical fiber cables installed in metal raceways without an overall nonmetallic

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covering, metal sheathed cable without an overall nonmetallic covering, or totally enclosed nonventilated busway without an overall nonmetallic covering are not considered to be exposed to the airflow and need not meet the requirements of 4.3.11 .4.6. Electrical wires and cables and optical fiber cables listed to UL 2424, Outline of Investigation for Cable Marked 'Limi­ted C<Jmbustible, ' are considered to be suitable for use wherever cables tested in accordance wid1 NFPA 262 are required.

A.4.3.11.5.5.1 Electrical wires and cables and optical fiber cables listed to UL 2424, Outline of Investigation for Cable Marked 'Limited Combustible,' are considered to be suitable fo1- use wher­

ever cables tested in accordance with NFPA 262 are required.

A.4.3.12.1.1 See ASHRAE 170, Ventilation of Health Care Facili­ties.

A.4.3.13 For further information, see NFPA 92.

A.4.4.1 The provisions of 4.4.1 do not require inherently noncombustible materials to be tested in order to be classified as noncombustible materials.

A.5.3 For examples of the application of the penetration protection requirements, see Figure A.5.3.

A.5.3.1.1 Duct penetrations of fire walls should be avoided.

A.5.3.1.1.1 Fire dampers are recommended in order to isolate specific hazards.

A.5.3.3 For information on designs of fire-resistive assemblies incorporating air-handling components, see UL Fire Resistance Directory, "Floor-Ceiling Designs" or "Roof-Ceiling Designs."

A.5.3.5.1.5 Smoke dampers exempted by NFPA 101 for health care occupancies include dampers in duct peneu-ations of smoke barriers in fully ducted heating, ventilating, and air­conditioning systems.

A.5.4.3 The designer should specify the leakage class, maxi­mum pressure, maximum velocity, installation mode (ho1-izon­tal or vertical) , and degradation test temperature of tl1e damper.

A.5.4.4.1 For information on other methods of protecting openings in rated floor-ceiling or roof�ceiling assemblies, see the UL Fire Resistance Directm·y design information section fo1-duct outlet protection. System A can be used only when it is specified in the individual design. System B can be used in any design that contains a steel duct with the duct outlet protected by a hinged door damper, for equal or smaller outlet size. The systems have been investigated for their effectiveness in retard­ing the transfe1- of heat into the ceiling space, but their ability to retard smoke and other combustion products has not been investigated.

A.5.4.5.2.2.l The exception to this paragraph in eadier editions applied to fire dampers, due to the fact that UL 555S, Smoke Dampers, which tested combination dampers, was not available. Fire dampers in acco1-dance with UL 555, Fire Damp­ers, are listed with maximum 141°C (286°F) links. It is recog­nized that, in some unusual cases, an engineered smoke­control system can make higher temperature links desirable fo1-proper operation. This arrangement necessitates a case-by-case consideration and concurrence by the authority having juris­diction.

Fire-rated roof-ceiling assem�y

Notes:

Return/exhaust duct requirements are similar.

SD = Smoke damper

FD = Fire damper

G) ©@ . . . . = Space identification

ANNEX A

FIGURE A.5.3 Application of Penetration Requirements.

A.5.4.5.4 On closure of certain smoke dampers in smoke­control systems, the total system flow decreases, but the duct velocity at open fire dampers can be as high as roughly 600 percent of the initial duct design velocity. The dynamic airflow and pressure rating of the darnpe1- must be adequate for the damper to close w1der airflow at the damper's closure pressure. The damper face velocity and closure pressure can be approximated by calculation. The calculated values must be specified because UL labels dynamic fire dampers at 5 m/sec ( 1 000 ft/min) increments, starting at 10 m/sec (2000 ft/min).

A.5.4.7.1 Fire dampe1-s are of no fire protection value unless they remain in place in the protected opening in the event that the ductwork collapses during a fire. To accomplish this, duct­w01-k should not be continuous through a partition opening but instead should connect on each side of the partition to a damper installed in a sleeve or frame secured by perimeter­mounting angles on both sides of d1e opening or be installed per the listing of the device. For specific details regarding sleeve thickness, perimeter angle dimensions, size and frequency of fa5teners, clearance for expansion, duct-sleeve connections, and fire damper access doors, the manufacturer's installation instructions and SMACNA Fire, Smoke and Radiation Damper Installation Guide for HVAC Systems should be referenced.

A.6.3 The dampers should close as quickly as practicable, subject to requirements of the system fan and air duct charac­teristics. The designer should evaluate wheilier the smoke dampers normally should be open or closed and should consider the fail-safe position of the dampers during an event such as a power failure.

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Exhaust fan

.---L,

A.6.3.2 v\Tithin the scope of th.is document, smoke dampers reduce the possibility of smoke transfer within ducnvork or through wall openings. Activation of smoke dampers can be by area detectors that are installed in the related smoke compart­ment or by detectors that are installed in the air duct systems. See NFPA 72.

A.6.3.4 Although permitted to remain open during fan shut­down, smoke dampers and combination fire and smoke damp­ers installed in smoke barriers should be arranged to close automatically when the fan system(s) d1ey are serving is not in operation.

A.6.4 The use of smoke detectors in relationship to HVAC systems and high air movement areas and the details regarding their optimum installation are covered in NFPA 72.

Protection provided by the installation of smoke detectors and related requirement5 is intended to prevent the distribu­tion of smoke ilirough the supply air duct system and, prefera­bly, to exhaust a significant quantity of smoke to the outside. Neither function, however, guarantees either d1e early detec­tion of fire or the detection of smoke concentrations prior to dangerous smoke conditions where smoke movement is od1er than through d1e supply air system.

Where smoke-control protection for a facility is determined to be needed, see NFPA 92.

A.6.4.2 The summation of the capacities of individual supply­air fans should be made where such fans are connected to a common supply air duct system (i.e., all fans connected to a common air duct supply system should be considered as consti-

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90A-22 INSTALLATION Or AJR-CONDITIONING AND VENTILATING SYSTEMS

tuting a single system with respect to the applicability of the Chapte1· 6 provisions that a1·e dependent on system capacity) .

A.6.4.3 V\fhere automatic water sprinklers are provided and zoned to coordinate with the HVAC zones, their water flow switches should initiate devices for the fimctions described in Chapter 6.

Sprinklers are often tested weekly. Where it is desirable to prevent the accompanying automatic shutdown of the fan system(s) referred to in 6.4.3, a means can be permitted to be used to avoid such shutdown temporarily, provided one of the following occurs:

( l ) A trouble signal is sustained in the sprinkler supervisory system until the automatic shutdown provision is restored.

(2) The automatic shutdown provision is restored at the end of the time period necessaty to test the sprinkler system, its alarms, and related elements.

A. 7.1. l Many of the fire protection meamres required in this standard are passive and fi.tnction only in emergencies. There­fore, acceptance testing needs to be performed so that all parts of ai.r-conditioning systems are ready for a fire emergency. The access openings required in 4.3.4 should be checked for proper location, function, and size dming the acceptance testing.

Maintenance recommendations, including cleaning, repair­ing, and periodic testing, are provided in Annex B.

A. 7.2 See NFPA 105 for testing requirements for smoke damp­ers and combination fire and smoke dampers. See NFPA 80 for testing requirements for fire dampers. AMCA International's Guide for Commissioning and Periodic Pe1f onnance Testing of Fire, Smoke and Other Life Safety Related Dampen provides guidelines from damper manufacturers on how to test dampers for accept­ance testing and for follow-up periodic testing.

A. 7.3. l Generally, tests can be included with acceptance test­ing of the air-conditioning controls or fire alarm systems.

Annex B Maintenance

This annex is not a part of the requirements of this NFPA document but i5 included for infmmational pmposes only.

B.l General.

B.l.l Owners should develop a greater awareness of the life and property protection abilities of air-conditioning systems and should establish a planned maintenance schedule. Failure to maintain proper conditions of cleanliness in air duct systems and carelessness in connection with repair operations have been important conu·ibuting causes of several fires that have involved air-conditioning systems. The recommendations in this annex apply, in general, to the period of operation of the system; systems operating only part of the yea1· should be given a thorough general checkup before starting operation and again after a shutdown.

B.l.2 The intervals of testing and maintenance vary widely, depending on the duration of system operation, condition of fresh air, amount of dust in return air, and other factors. The intervals specified in this standard are intended to be the maxi­mum and should be shortened if system conditions warrant.

B.l.3 The use of an inspection form to obtain a thorough inspection is recommended. The fonn should fit the system or

2021 Edition

systems involved, listing the items needing attention. However, it is recommended that provision be made on the form fo1· equipment location, inspection frequency, clue elate, inspection date, inspector, and record of discrepancies found.

B.2 Frre Dampers, Smoke Dampers, and Ceiling Dampers.

B.2.1 Refer to NFPA 80 for inspection and maintenance of fire dampers, ceiling dampers, and combination fire/smoke dampern.

B.2.2 Refer to NFPA 105 for inspection and maintenance of smoke dampers and combination fire/smoke dampers.

B.2.3 Refer to NFPA 92 for maintenance of smoke and combi­nation fire/smoke dampers for each damper installed as part of a smoke control system.

B.3 Filters.

B.3.1 All air filters should be kept free of excess dust and combustible material. Unit filters should be renewed or cleaned when the resistance to airflow has increased to two times the original resistance or when the resistance has reached a value of recommended replacement by the manufac­turer. A suitable draft gauge should be provided for the purpose. Where the filters are of the automatic liquid adhesive type, sludge should be removed from the liquid adhesive reser­voir regularly.

B.3.2 V1fhen filters are replaced, care should be taken to use the proper type and size and to avoid gaps between filter sections, mounting frames, 01· hardware. Damaged filter sections or media should not be used.

B.3.3 Filters designed and manufactmed to be thrown away after use should never be cleaned and reused.

B.3.4 Care should be exercised in the use of liquid adhesives. Use of an adhesive with a low flash point creates a serious hazard.

B.3.5 Electrical equipment of automatic filters should be inspected semiannually and the operation cycle obsetved to ensure that the moto1·, relays, and other conu·ols function as intended. Drive motors and gear reductions also should be inspected at least semiannually and lubricated when necessa1y.

B.4 Inspection and Cleaning of Ducts.

B.4.1 Inspections to determine the amount of dust and waste material in the ducts (both discharge and return) should be made quarterly. If, after several inspections, such frequent inspection is determined to be unnecessary, the interval between inspections can be permitted to be adjusted to suit the conditions.

B.4.2 Cleaning should be undertaken whenever an inspection indicates the need.

B.4.3 Cooling and heating coils should be cleaned, if neces­sary, at the time ducts are cleaned. Thorough cleaning of ducts can require scraping, brushing, or other positive means. Vacuum cleaning might not remove dust of an oily or sticky nature or heavy accumulations in the elbows or seams. The amount and kind of dust and dirt depend greatly on the occu­pancy and the arrangement of the duct system. Additional access doors or panels could be needed to allow complete cleaning of duct systems.

ANNEX C

B.5 Inspection and Cleaning of Plenums.

B.5.1 Apparatus casing and air-handling unit plenums should be inspected monthly. If, after several inspections, such frequent inspection is determined to be unnecessary, the inter­val between inspections can be adjusted to suit the conditions.

B.5.2 Ceiling cavity plenums, raised floor plenums, and duct distribution plenums should be inspected in a manner similar to that of ducts, beginning with quarterly inspections and adjusting the frequency to suit dirt buildup conditions.

B.5.3 Cleaning should be undertaken whenever an inspection indicates the need, especially in common plenums serving more than one fan or system. V\There plenum chambers could be used for storage, arrangements, such as keeping the doors locked, should be made to prevent such usage. (See 4. 3.10.)

B.6 Repair Work. Extreme caution should be exercised in the use of open flames or spark-emitting devices inside duct5 or plenum chambers or near air intakes.

B.7 Outside Air Intakes.

B.7.1 Conditions outside the outside air intake should be examined at the time duct5 are inspected. Items to be noted include the following:

( 1 ) Accumulations of combustible material near the intake (2) The presence of buildings or structures that could

present an exposure to the intake, allowing smoke and fire to be drawn in

(3) The operating condition of any automatic damper designed to protect the opening against exposure fire

B.7.2 'Where accumulations of combustible material ai·e noted, they should be removed immediately and arrangements made to avoid such accumulations. Inspections thereafter should be made more frequently. If newly erected exposures are noticed, consideration should be given to the protection at the intake to ensure that it is adequate. (See 4.3. 7.)

B.8 Fans and Fan Motors.

B.8.1 Fans and fan motors should be inspected at least quar­terly and cleaned and lubricated when necessary. Care should be exercised in lubricating fans to prevent lubricant from running onto the fan blades. Fans also should be checked for alignment and checked to see that they are running freely.

B.8.2 The alignment of fan belt drives should be checked, because improper alignment can cause motor overheating as well as premature belt failure.

B.9 Controls. Fan contwls should be examined and activated at least annually to ensure that they are in operable condition.

Annex C Informational References

C.l Referenced Publications. The documents or portions thereof listed in this annex are referenced within the informa­tional sections of this standard and are not part of the require­ments of this document unless also listed in Chapter 2 for othe1- reasons.

C.1.1 NFPA Publications. National Fire Protection Associa­tion, 1 Batterymarch Park, Quincy, MA 02169-7471 .

NFPA 31, Standard for the Installation of Oil-Burning Equipment, 2020 edition.

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NFPA 33, Standard for Spray Application Using Flammable or Combustible Materials, 2021 edition.

NFPA 34, Standard for Dipping, Coating, and Printing Processes U5ing Flammable or Cmnlrustible Liquids, 2021 edition.

NFPA 45, Standard on Fire Protection for Laboratories Using Chem­icals, 2019 edition.

NFPA 7rJID, National Electrical Cod�. 2020 edition.

NFPA J:;!ID, National Fire Alarm and Signaling Co�. 2019 edition.

NFPA 75, Standard for the Fire Protection of Information Technol­og;1 Equipment, 2020 edition.

NFPA 80, Standard for Fire Doors and Other opening Protectives, 2019 edition.

NFPA 90B, Standard for the Installation of Wann Air Heating and Air-Conditioning Systems, 2021 edition.

NFPA 91, Standard for Exhaust Systems for Air Conveying of Vapors, Gases, Mists, and Particulate Solids, 2020 edition.

NFPA 92, Standard for Smoke Control Systems, 2021 edition.

NFPA 96, Standard for Ventilation Control and Fire Protection of Commercial Cooking Operations, 2021 edition.

NFPA 101®, Life Safety Codi?, 2021 edition.

NFPA 105, Standard for Smoke Door Assemblies and Other open­ing Protectives, 2019 edition.

NFPA 220, Standard on Types of Building Construction, 2021 edition.

NFPA 259, Standard Jest Method for Potential Heat of Building Materials, 2018 edition.

NFPA 262, Standard Method of Test for Flame Travel and Smoke of Win1s and Cables for Use in Air-Handling Spaces, 2019 edition.

C.1.2 Other Publications.

C.1.2.1 ASHRAE Publications. ASHRAE, 1791 Tullie Circle, NE, Atlanta, GA 30329-2305.

ASHRAE 170, Ventilation of Health Care Facilities (ANSI/ ASH RAE/ ASHE Approved), 2017.

ASHRAE Handbook - Fundamentals (1-P), 2017.

C.1.2.2 AMCA Publications. Air Movement and Control Asso­ciation International, Inc., 30 v\Test University Drive, Arlington Heights, IL 60004-1893.

Gu:ide for Commissioning and Periodic Pe1f onnance Testing of Fire, Smoke and Other Life Safety Related Dampers, 201 1 .

C.1.2.3 ASTM Publications. ASTM International, 100 Ban­Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959.

ASTM E84, Standard Test Method for SU1f ace Burning Character­istics of Bui lding Materials, 2019b.

ASTM El36, Standard Test Method for Assessing Combustibility of Materials U�ing a Vertical Tube Furnace at 750°C, 2019.

ASTM E22 3 1 , Standard Practice for Specimen Preparation and Mounting of Pipe and Duct Inmlation Materials to Assess SU1face Burning Characteristics, 2018.

2021 Edition

90A-24 INSTALLATION Or AJR-CONDITIONING AND VENTILATING SYSTEMS

ASTM E2652, Standard Test Method for Assessing Combustibility of Materials Using a Tube Furnace with a Cone-Shaped Ai:ljlow Stabil­izer, at 750°C, 2018.

C.1.2.4 NAIMA Publications. North American Insulation Manufacturers Association, 1 1 Canal Center Plaza, Suite 103, Alexandria, VA 22314.

Fibrous G/,ass Duct Liner Standard, 3rd edition, 2002.

Fibrous Gwss Duct Construction Standards, 7th edition, 2003.

C.1.2.5 SMACNA Publications. Sheet Metal and Air Condi­tioning Contractors' National Association, 4201 Lafayette Center Drive, Chantilly, VA 20151-1219.

Fire, Smoke and Radiation Dam.per Installation Guide for HVAC S)'stems, 2002.

C.1.2.6 UL Publications. Underwriters Laboratories Inc., 333 Pfingsten Road, Northbrook, IL 60062-2096.

UL 555, FfreDam.pers, 2006, revised 2016.

UL 555S, Smoke Dampers, 2014, 1·evised 2016.

2021 Edition

UL 1565, Positioning Devices, 2013, revised 2017.

UL 2043, Fire Test for Heat and Visible Smoke Release for Discrete Products and Their Accessories Installed in Air-Handling Spaces, 2013.

UL 2424, Outline of Investigation for Cable M(l1ked 'Limited C.Om.bustible, ' 2006.

UL 62275, Cable Management S)'stem.s - Cable Ties for Elect1ical Installations, 2016.

Building Mate1ialsDirector)', 2018.

Fire Resistance Dfrect01y, 2018.

Heating, Cooling, Ventilating and Cooking Equipment Direct01y, 2018.

C.2 Informational References. (Reserved)

C.3 References for Extracts in Informational Sections. (Reserved)

INDEX 90A-25

Index

Copyright © 2020 National Fire Protection Association. All Rights Reserved.

The copyright in this index is separate and distinct from the copyright in the document that it indexes. The Licensing provi­sions set forth for the document are not applicable to this index. This index may not be reproduced in whole or in part by any means without the express written permission of NFPA.

-A-

Acceptance Testing, Chap. 7

Controls and Operating Systems, 7.3

Fire Dampers, Smoke Dampers, and Ceiling Dampers, 7.2, A. 7.2

Access, 7.2.1

Testing, 7.2.3

General, 7.1

Accessible

Definition, 3.3.1

Administration, Chap. l

Application, 1.3

Equivalency, 1.5

Purpose, l.2

Retroactivity, l.4

Scope, 1.1, A. l . l

Air Cleaner

Definition, 3.3.2

Air Connector

Definition, 3.3.3, A.3.3.3

Air Distribution System

Definition, 3.3.4

Air Duct

Definition, 3.3.5

Air Duct Covering

Definition, 3.3.6

Air Duct Lining

Definition, 3.3.7

Air Filter

Definition, 3.3.8

Air Inlet

Definition, 3.3.9, A.3.3.9

Air Outlet

Definition, 3.3.10, A.3.3.IO

Air Terminal Unit

Definition, 3.3.l l

Air 'Iransfer Opening

Definition, 3.3.12

Approved

Definition, 3.2.1, A.3.2.l

Authority HavingJurisdiction (AHJ)

Definition, 3.2.2, A.3.2.2

-C-

Continued Progressive Combustion

Definition, 3.3.13

Controls, Chap. 6

Manual Control, 6.2

Smoke Dampers, 6.3, A.6.3

Smoke Detection for Automatic Control, 6.4, A.6.4

Function, 6.4.3, A.6.4.3

Installation, 6.4.4

Location, 6.4.2, A.6.4.2

Testing, 6.4.l

Wiring, 6.1

Damper

Ceiling Damper

-D-

Definition, 3.3.I4. l , A.3.3.I4.l

Combination Fire and Smoke Damper

Definition, 3.3. 14.2

Definition, 3.3. 14

Fire Damper

Definition, 3.3.I4.3, A.3.3.I4.3

Smoke Damper

Definition, 3.3.14.4, A.3.3.14.4

Definitions, Chap. 3

Environmental Air Definition, 3.3.15

Explanatory Material, Annex A

Fan

Definition, 3.3. 16

Fire Resistance Rating

Definition, 3.3.17, A.3.3. 17

Fire Wall

Definition, 3.3. 18

Flame Spread Index

Definition, 3.3.19, A.3.3.19

Foam Plastic Insulation

Definition, 3.3.20

HVAC Systems, Chap. 4

Air Distribution, 4.3, A.4.3

Air Connectors, 4.3.2

-E-

-F-

-H-

Air Duct Access and Inspection, 4.3.5

Air Duct Integrity, 4.3.6

Air Ducts, 4.3.1

Air Dispersion Systems, 4.3.l .8

Gypsum Board Air Ducts, 4.3. l.3

Air Inlets - Return or Exhaust or Return and Exhaust, 4.3.8

Construction of Air Inlets, 4.3.8.2

General, 4.3.8. l

Location of Air Inlets, 4.3.8.3

Air Outlets, 4.3. 7

Construction of Air Ourlets, 4.3.7.2

2021 Edition

90A-26 INSTALLATION OF AJR-CONDITIONING AND VENTILATING SYSTEMS

General, 4.3.7.l

Location of Air Outlecs, 4.3.7.3

Corridor Air Systems, 4.3.12

Egress Corridors, 4.3.12.1

Exits, 4.3.12.2

Fire Dampers, 4.3.9

Materials for Operation and Conu-ol of tl1e Air Distribution System, 4.3.4

Plenums, 4.3.11

Ai1�Handling Unit Room Plenum, 4.3.1 l . 4

Apparams Casing Plenum, 4.3.1 1.3

Ceiling Cavity Plenum, 4.3.11.2

Raised Floor Plenum, 4.3.11.5

Storage, 4.3. 1 1 . 1

Wall o r Ceiling Finish i n Plenums, 4.3.11.6

Smoke Control, 4.3.13, A.4.3.13

Smoke Dampers, 4.3.10

Supplementary Materials for Air Disu·ibution Systems, 4.3.3

General Requiremencs for Equipment, 4.1

Access, 4.1.1

Protection, 4.1.3

Materia Is, 4.4

Limited-Combustible Material, 4.4.2

Noncombustible Material, 4.4.1, A.4.4.1

System Componencs, 4.2

Air Cleaners and Air Filters, 4.2.2

Air-Cooling and Heating Equipment, 4.2.4

Duct Heaters, 4.2.4.5

Evaporative Coolers, 4.2.4.6

Furnaces, 4.2 .4.4

Heat Recovery Equipment, 4.2.4.7

Installation, 4.2.4.l

Materials, 4.2.4.2

Mechanical Cooling, 4.2.4.3

Fans, 4.2.3

Access, 4.2.3.2

Exposed Inlets, 4.2.3.3

Installation, 4.2.3.1

Oucside Air Intakes, 4.2.I

-I-

Informational References, Annex C

Integration of a Ventilation and Air-Conditioning System(s) with Building Construction, Chap. 5

Air-Handling Equipment Rooms, 5.1

Air-Handling Equipment Rooms That Have Air Duccs That Open Directly into a Shaft, 5.1.3

Air-Handling Equipment Rooms Used as Plenum Space, 5.1.2

General, 5.1.1

Other Spaces Housing Air-Handling Units, 5.1.4

Building Construction, 5.2

Air Duct Clearance, 5.2.1

Ceiling Assemblies, 5.2.3

Structural Members, 5.2.2

Fire Dampers, Smoke Dampers, and Ceiling Dampers, 5.4

Ceiling Dampers, 5.4.4

Dam per Closure, 5.4.5

2021 Edition

Fusible Links, 5.4.5.2

Damper Location Information, 5.4.6

Fire Dampers, 5.4.l

Installation, 5.4.7

Maintenance, 5.4.8

Smoke Dampers, 5.4.3, A.5.4.3

Peneu-ations - Protection of Openings, 5.3, A.5.3

Fire-Rated Walls and Partitions, 5.3.1

Floor-Ceiling or Roof�Ceiling A5semblies Having a Fire Resistance Rating, 5.3.3, A.5.3.3

Floors Required to Have a Fire Resistance Rating, 5.3.2

Shafcs, 5.3.4

Smoke Barriers, 5.3.5

Limited-Combustible (Material)

Definition, 3.3.21, A.3.3.21

Listed

Definition, 3.2.3, A.3.2.3

Maintenance, Annex B

Controls, B.9

Fans and Fan Motors, B.8

Filters, B.3

-L-

-M-

Fire Dampers, Smoke Dampers, and Ceiling Dampers, B.2

General, B.l

Inspection and Cleaning ofDuccs, B.4

Inspection and Cleaning of Plenums, B.5

Outside Air Intakes, B.7

Repair Work, B.6

Noncombustible Material

Definition, 3.3.22, A.3.3.22

Plenum

-N-

-P-

Air-Handling Unit Room Plenum

Definition, 3.3.23.l

Apparatus Casing Plenum

Definition, 3.3.23.2

Ceiling Cavity Plenum

Definition, 3.3.23.3

Definition, 3.3.23, A.3.3.23

Raised Floor Plenum

Definition, 3.3.23.4

-R-

Referenced Publications, Chap. 2

Shall

Definition, 3.2.4

Should

Definition, 3.2.5

Smoke

Definition, 3.3.24

.S-

Smoke Barrier

Definition, 3.3.25, A.3.3.25

Smoke Control

Definition, 3.3.26

Smoke Detector

Definition, 3.3.27, A.3.3.27

INDEX

Smoke Developed Index

Definition, 3.3.28, A.3.3.28

Standard

Definition, 3.2.6

90A-27

2021 Edition